src/pdf/SkPDFShader.cpp - platform/external/skqp - Gitiles

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */


 #include "SkPDFShader.h"

 #include "SkData.h"
 #include "SkPDFCanon.h"
 #include "SkPDFDevice.h"
 #include "SkPDFDocumentPriv.h"
 #include "SkPDFFormXObject.h"
 #include "SkPDFGradientShader.h"
 #include "SkPDFGraphicState.h"
 #include "SkPDFResourceDict.h"
 #include "SkPDFUtils.h"
 #include "SkScalar.h"
 #include "SkStream.h"
 #include "SkSurface.h"
 #include "SkTemplates.h"


 static void draw_image_matrix(SkCanvas* canvas, const SkImage* img,
                               const SkMatrix& matrix, const SkPaint& paint) {
     SkAutoCanvasRestore acr(canvas, true);
     canvas->concat(matrix);
     canvas->drawImage(img, 0, 0, &paint);
 }

 static void draw_bitmap_matrix(SkCanvas* canvas, const SkBitmap& bm,
                                const SkMatrix& matrix, const SkPaint& paint) {
     SkAutoCanvasRestore acr(canvas, true);
     canvas->concat(matrix);
     canvas->drawBitmap(bm, 0, 0, &paint);
 }

 static sk_sp<SkPDFStream> make_image_shader(SkPDFDocument* doc,
                                             const SkPDFImageShaderKey& key,
                                             SkImage* image) {
     SkASSERT(image);

     // The image shader pattern cell will be drawn into a separate device
     // in pattern cell space (no scaling on the bitmap, though there may be
     // translations so that all content is in the device, coordinates > 0).

     // Map clip bounds to shader space to ensure the device is large enough
     // to handle fake clamping.
     SkMatrix finalMatrix = key.fCanvasTransform;
     finalMatrix.preConcat(key.fShaderTransform);
     SkRect deviceBounds = SkRect::Make(key.fBBox);
     if (!SkPDFUtils::InverseTransformBBox(finalMatrix, &deviceBounds)) {
         return nullptr;
     }

     SkRect bitmapBounds = SkRect::Make(image->bounds());

     // For tiling modes, the bounds should be extended to include the bitmap,
     // otherwise the bitmap gets clipped out and the shader is empty and awful.
     // For clamp modes, we're only interested in the clip region, whether
     // or not the main bitmap is in it.
     SkShader::TileMode tileModes[2];
     tileModes[0] = key.fImageTileModes[0];
     tileModes[1] = key.fImageTileModes[1];
     if (tileModes[0] != SkShader::kClamp_TileMode ||
             tileModes[1] != SkShader::kClamp_TileMode) {
         deviceBounds.join(bitmapBounds);
     }

     SkISize patternDeviceSize = {SkScalarCeilToInt(deviceBounds.width()),
                                  SkScalarCeilToInt(deviceBounds.height())};
     auto patternDevice = sk_make_sp<SkPDFDevice>(patternDeviceSize, doc);
     SkCanvas canvas(patternDevice);

     SkRect patternBBox = SkRect::Make(image->bounds());

     // Translate the canvas so that the bitmap origin is at (0, 0).
     canvas.translate(-deviceBounds.left(), -deviceBounds.top());
     patternBBox.offset(-deviceBounds.left(), -deviceBounds.top());
     // Undo the translation in the final matrix
     finalMatrix.preTranslate(deviceBounds.left(), deviceBounds.top());

     // If the bitmap is out of bounds (i.e. clamp mode where we only see the
     // stretched sides), canvas will clip this out and the extraneous data
     // won't be saved to the PDF.
     canvas.drawImage(image, 0, 0);

     SkScalar width = SkIntToScalar(image->width());
     SkScalar height = SkIntToScalar(image->height());

     SkPaint paint;
     paint.setColor(key.fPaintColor);
     // Tiling is implied.  First we handle mirroring.
     if (tileModes[0] == SkShader::kMirror_TileMode) {
         SkMatrix xMirror;
         xMirror.setScale(-1, 1);
         xMirror.postTranslate(2 * width, 0);
         draw_image_matrix(&canvas, image, xMirror, paint);
         patternBBox.fRight += width;
     }
     if (tileModes[1] == SkShader::kMirror_TileMode) {
         SkMatrix yMirror;
         yMirror.setScale(SK_Scalar1, -SK_Scalar1);
         yMirror.postTranslate(0, 2 * height);
         draw_image_matrix(&canvas, image, yMirror, paint);
         patternBBox.fBottom += height;
     }
     if (tileModes[0] == SkShader::kMirror_TileMode &&
             tileModes[1] == SkShader::kMirror_TileMode) {
         SkMatrix mirror;
         mirror.setScale(-1, -1);
         mirror.postTranslate(2 * width, 2 * height);
         draw_image_matrix(&canvas, image, mirror, paint);
     }

     // Then handle Clamping, which requires expanding the pattern canvas to
     // cover the entire surfaceBBox.

     SkBitmap bitmap;
     if (tileModes[0] == SkShader::kClamp_TileMode ||
         tileModes[1] == SkShader::kClamp_TileMode) {
         // For now, the easiest way to access the colors in the corners and sides is
         // to just make a bitmap from the image.
         if (!SkPDFUtils::ToBitmap(image, &bitmap)) {
             bitmap.allocN32Pixels(image->width(), image->height());
             bitmap.eraseColor(0x00000000);
         }
     }

     // If both x and y are in clamp mode, we start by filling in the corners.
     // (Which are just a rectangles of the corner colors.)
     if (tileModes[0] == SkShader::kClamp_TileMode &&
             tileModes[1] == SkShader::kClamp_TileMode) {
         SkASSERT(!bitmap.drawsNothing());
         SkPaint paint;
         SkRect rect;
         rect = SkRect::MakeLTRB(deviceBounds.left(), deviceBounds.top(), 0, 0);
         if (!rect.isEmpty()) {
             paint.setColor(bitmap.getColor(0, 0));
             canvas.drawRect(rect, paint);
         }

         rect = SkRect::MakeLTRB(width, deviceBounds.top(),
                                 deviceBounds.right(), 0);
         if (!rect.isEmpty()) {
             paint.setColor(bitmap.getColor(bitmap.width() - 1, 0));
             canvas.drawRect(rect, paint);
         }

         rect = SkRect::MakeLTRB(width, height,
                                 deviceBounds.right(), deviceBounds.bottom());
         if (!rect.isEmpty()) {
             paint.setColor(bitmap.getColor(bitmap.width() - 1,
                                            bitmap.height() - 1));
             canvas.drawRect(rect, paint);
         }

         rect = SkRect::MakeLTRB(deviceBounds.left(), height,
                                 0, deviceBounds.bottom());
         if (!rect.isEmpty()) {
             paint.setColor(bitmap.getColor(0, bitmap.height() - 1));
             canvas.drawRect(rect, paint);
         }
     }

     // Then expand the left, right, top, then bottom.
     if (tileModes[0] == SkShader::kClamp_TileMode) {
         SkASSERT(!bitmap.drawsNothing());
         SkIRect subset = SkIRect::MakeXYWH(0, 0, 1, bitmap.height());
         if (deviceBounds.left() < 0) {
             SkBitmap left;
             SkAssertResult(bitmap.extractSubset(&left, subset));

             SkMatrix leftMatrix;
             leftMatrix.setScale(-deviceBounds.left(), 1);
             leftMatrix.postTranslate(deviceBounds.left(), 0);
             draw_bitmap_matrix(&canvas, left, leftMatrix, paint);

             if (tileModes[1] == SkShader::kMirror_TileMode) {
                 leftMatrix.postScale(SK_Scalar1, -SK_Scalar1);
                 leftMatrix.postTranslate(0, 2 * height);
                 draw_bitmap_matrix(&canvas, left, leftMatrix, paint);
             }
             patternBBox.fLeft = 0;
         }

         if (deviceBounds.right() > width) {
             SkBitmap right;
             subset.offset(bitmap.width() - 1, 0);
             SkAssertResult(bitmap.extractSubset(&right, subset));

             SkMatrix rightMatrix;
             rightMatrix.setScale(deviceBounds.right() - width, 1);
             rightMatrix.postTranslate(width, 0);
             draw_bitmap_matrix(&canvas, right, rightMatrix, paint);

             if (tileModes[1] == SkShader::kMirror_TileMode) {
                 rightMatrix.postScale(SK_Scalar1, -SK_Scalar1);
                 rightMatrix.postTranslate(0, 2 * height);
                 draw_bitmap_matrix(&canvas, right, rightMatrix, paint);
             }
             patternBBox.fRight = deviceBounds.width();
         }
     }

     if (tileModes[1] == SkShader::kClamp_TileMode) {
         SkASSERT(!bitmap.drawsNothing());
         SkIRect subset = SkIRect::MakeXYWH(0, 0, bitmap.width(), 1);
         if (deviceBounds.top() < 0) {
             SkBitmap top;
             SkAssertResult(bitmap.extractSubset(&top, subset));

             SkMatrix topMatrix;
             topMatrix.setScale(SK_Scalar1, -deviceBounds.top());
             topMatrix.postTranslate(0, deviceBounds.top());
             draw_bitmap_matrix(&canvas, top, topMatrix, paint);

             if (tileModes[0] == SkShader::kMirror_TileMode) {
                 topMatrix.postScale(-1, 1);
                 topMatrix.postTranslate(2 * width, 0);
                 draw_bitmap_matrix(&canvas, top, topMatrix, paint);
             }
             patternBBox.fTop = 0;
         }

         if (deviceBounds.bottom() > height) {
             SkBitmap bottom;
             subset.offset(0, bitmap.height() - 1);
             SkAssertResult(bitmap.extractSubset(&bottom, subset));

             SkMatrix bottomMatrix;
             bottomMatrix.setScale(SK_Scalar1, deviceBounds.bottom() - height);
             bottomMatrix.postTranslate(0, height);
             draw_bitmap_matrix(&canvas, bottom, bottomMatrix, paint);

             if (tileModes[0] == SkShader::kMirror_TileMode) {
                 bottomMatrix.postScale(-1, 1);
                 bottomMatrix.postTranslate(2 * width, 0);
                 draw_bitmap_matrix(&canvas, bottom, bottomMatrix, paint);
             }
             patternBBox.fBottom = deviceBounds.height();
         }
     }

     auto imageShader = sk_make_sp<SkPDFStream>(patternDevice->content());
     sk_sp<SkPDFDict> resourceDict = patternDevice->makeResourceDict();
     SkPDFUtils::PopulateTilingPatternDict(imageShader->dict(), patternBBox,
                                           std::move(resourceDict), finalMatrix);
     return imageShader;
 }

 // Generic fallback for unsupported shaders:
 //  * allocate a surfaceBBox-sized bitmap
 //  * shade the whole area
 //  * use the result as a bitmap shader
 static sk_sp<SkPDFObject> make_fallback_shader(SkPDFDocument* doc,
                                                SkShader* shader,
                                                const SkMatrix& canvasTransform,
                                                const SkIRect& surfaceBBox,
                                                SkColor paintColor) {
     // TODO(vandebo) This drops SKComposeShader on the floor.  We could
     // handle compose shader by pulling things up to a layer, drawing with
     // the first shader, applying the xfer mode and drawing again with the
     // second shader, then applying the layer to the original drawing.
     SkPDFImageShaderKey key = {
         canvasTransform,
         SkMatrix::I(),
         surfaceBBox,
         {{0, 0, 0, 0}, 0},  // don't need the key; won't de-dup.
         {SkShader::kClamp_TileMode, SkShader::kClamp_TileMode},
         paintColor};

     key.fShaderTransform = shader->getLocalMatrix();

     // surfaceBBox is in device space. While that's exactly what we
     // want for sizing our bitmap, we need to map it into
     // shader space for adjustments (to match
     // MakeImageShader's behavior).
     SkRect shaderRect = SkRect::Make(surfaceBBox);
     if (!SkPDFUtils::InverseTransformBBox(canvasTransform, &shaderRect)) {
         return nullptr;
     }
     // Clamp the bitmap size to about 1M pixels
     static const SkScalar kMaxBitmapArea = 1024 * 1024;
     SkScalar bitmapArea = surfaceBBox.width() * surfaceBBox.height();
     SkScalar rasterScale = 1.0f;
     if (bitmapArea > kMaxBitmapArea) {
         rasterScale *= SkScalarSqrt(kMaxBitmapArea / bitmapArea);
     }

     SkISize size = {SkScalarRoundToInt(rasterScale * surfaceBBox.width()),
                     SkScalarRoundToInt(rasterScale * surfaceBBox.height())};
     SkSize scale = {SkIntToScalar(size.width()) / shaderRect.width(),
                     SkIntToScalar(size.height()) / shaderRect.height()};

     auto surface = SkSurface::MakeRasterN32Premul(size.width(), size.height());
     SkCanvas* canvas = surface->getCanvas();
     canvas->clear(SK_ColorTRANSPARENT);

     SkPaint p;
     p.setShader(sk_ref_sp(shader));
     p.setColor(paintColor);

     canvas->scale(scale.width(), scale.height());
     canvas->translate(-shaderRect.x(), -shaderRect.y());
     canvas->drawPaint(p);

     key.fShaderTransform.setTranslate(shaderRect.x(), shaderRect.y());
     key.fShaderTransform.preScale(1 / scale.width(), 1 / scale.height());

     sk_sp<SkImage> image = surface->makeImageSnapshot();
     return make_image_shader(doc, key, image.get());
 }

 static SkColor adjust_color(SkShader* shader, SkColor paintColor) {
     if (SkImage* img = shader->isAImage(nullptr, nullptr)) {
         if (img->isAlphaOnly()) {
             return paintColor;
         }
     }
     // only preserve the alpha.
     return paintColor & SK_ColorBLACK;
 }

 sk_sp<SkPDFObject> SkPDFMakeShader(SkPDFDocument* doc,
                                   SkShader* shader,
                                   const SkMatrix& canvasTransform,
                                   const SkIRect& surfaceBBox,
                                   SkColor paintColor) {
     SkASSERT(shader);
     SkASSERT(doc);
     if (SkShader::kNone_GradientType != shader->asAGradient(nullptr)) {
         return SkPDFGradientShader::Make(doc, shader, canvasTransform, surfaceBBox);
     }
     if (surfaceBBox.isEmpty()) {
         return nullptr;
     }
     SkBitmap image;
     SkPDFImageShaderKey key = {
         canvasTransform,
         SkMatrix::I(),
         surfaceBBox,
         {{0, 0, 0, 0}, 0},
         {SkShader::kClamp_TileMode, SkShader::kClamp_TileMode},
         adjust_color(shader, paintColor)};

     SkASSERT(shader->asAGradient(nullptr) == SkShader::kNone_GradientType) ;
     if (SkImage* skimg = shader->isAImage(&key.fShaderTransform, key.fImageTileModes)) {
         key.fBitmapKey = SkBitmapKeyFromImage(skimg);
         SkPDFCanon* canon = doc->canon();
         sk_sp<SkPDFObject>* shaderPtr = canon->fImageShaderMap.find(key);
         if (shaderPtr) {
             return *shaderPtr;
         }
         sk_sp<SkPDFObject> pdfShader = make_image_shader(doc, key, skimg);
         canon->fImageShaderMap.set(std::move(key), pdfShader);
         return pdfShader;
     }
     // Don't bother to de-dup fallback shader.
     return make_fallback_shader(doc, shader, canvasTransform, surfaceBBox, key.fPaintColor);
 }
	/*
	* Copyright 2011 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/


	#include "SkPDFShader.h"

	#include "SkData.h"
	#include "SkPDFCanon.h"
	#include "SkPDFDevice.h"
	#include "SkPDFDocumentPriv.h"
	#include "SkPDFFormXObject.h"
	#include "SkPDFGradientShader.h"
	#include "SkPDFGraphicState.h"
	#include "SkPDFResourceDict.h"
	#include "SkPDFUtils.h"
	#include "SkScalar.h"
	#include "SkStream.h"
	#include "SkSurface.h"
	#include "SkTemplates.h"


	static void draw_image_matrix(SkCanvas* canvas, const SkImage* img,
	const SkMatrix& matrix, const SkPaint& paint) {
	SkAutoCanvasRestore acr(canvas, true);
	canvas->concat(matrix);
	canvas->drawImage(img, 0, 0, &paint);
	}

	static void draw_bitmap_matrix(SkCanvas* canvas, const SkBitmap& bm,
	const SkMatrix& matrix, const SkPaint& paint) {
	SkAutoCanvasRestore acr(canvas, true);
	canvas->concat(matrix);
	canvas->drawBitmap(bm, 0, 0, &paint);
	}

	static sk_sp<SkPDFStream> make_image_shader(SkPDFDocument* doc,
	const SkPDFImageShaderKey& key,
	SkImage* image) {
	SkASSERT(image);

	// The image shader pattern cell will be drawn into a separate device
	// in pattern cell space (no scaling on the bitmap, though there may be
	// translations so that all content is in the device, coordinates > 0).

	// Map clip bounds to shader space to ensure the device is large enough
	// to handle fake clamping.
	SkMatrix finalMatrix = key.fCanvasTransform;
	finalMatrix.preConcat(key.fShaderTransform);
	SkRect deviceBounds = SkRect::Make(key.fBBox);
	if (!SkPDFUtils::InverseTransformBBox(finalMatrix, &deviceBounds)) {
	return nullptr;
	}

	SkRect bitmapBounds = SkRect::Make(image->bounds());

	// For tiling modes, the bounds should be extended to include the bitmap,
	// otherwise the bitmap gets clipped out and the shader is empty and awful.
	// For clamp modes, we're only interested in the clip region, whether
	// or not the main bitmap is in it.
	SkShader::TileMode tileModes[2];
	tileModes[0] = key.fImageTileModes[0];
	tileModes[1] = key.fImageTileModes[1];
	if (tileModes[0] != SkShader::kClamp_TileMode \|\|
	tileModes[1] != SkShader::kClamp_TileMode) {
	deviceBounds.join(bitmapBounds);
	}

	SkISize patternDeviceSize = {SkScalarCeilToInt(deviceBounds.width()),
	SkScalarCeilToInt(deviceBounds.height())};
	auto patternDevice = sk_make_sp<SkPDFDevice>(patternDeviceSize, doc);
	SkCanvas canvas(patternDevice);

	SkRect patternBBox = SkRect::Make(image->bounds());

	// Translate the canvas so that the bitmap origin is at (0, 0).
	canvas.translate(-deviceBounds.left(), -deviceBounds.top());
	patternBBox.offset(-deviceBounds.left(), -deviceBounds.top());
	// Undo the translation in the final matrix
	finalMatrix.preTranslate(deviceBounds.left(), deviceBounds.top());

	// If the bitmap is out of bounds (i.e. clamp mode where we only see the
	// stretched sides), canvas will clip this out and the extraneous data
	// won't be saved to the PDF.
	canvas.drawImage(image, 0, 0);

	SkScalar width = SkIntToScalar(image->width());
	SkScalar height = SkIntToScalar(image->height());

	SkPaint paint;
	paint.setColor(key.fPaintColor);
	// Tiling is implied. First we handle mirroring.
	if (tileModes[0] == SkShader::kMirror_TileMode) {
	SkMatrix xMirror;
	xMirror.setScale(-1, 1);
	xMirror.postTranslate(2 * width, 0);
	draw_image_matrix(&canvas, image, xMirror, paint);
	patternBBox.fRight += width;
	}
	if (tileModes[1] == SkShader::kMirror_TileMode) {
	SkMatrix yMirror;
	yMirror.setScale(SK_Scalar1, -SK_Scalar1);
	yMirror.postTranslate(0, 2 * height);
	draw_image_matrix(&canvas, image, yMirror, paint);
	patternBBox.fBottom += height;
	}
	if (tileModes[0] == SkShader::kMirror_TileMode &&
	tileModes[1] == SkShader::kMirror_TileMode) {
	SkMatrix mirror;
	mirror.setScale(-1, -1);
	mirror.postTranslate(2 * width, 2 * height);
	draw_image_matrix(&canvas, image, mirror, paint);
	}

	// Then handle Clamping, which requires expanding the pattern canvas to
	// cover the entire surfaceBBox.

	SkBitmap bitmap;
	if (tileModes[0] == SkShader::kClamp_TileMode \|\|
	tileModes[1] == SkShader::kClamp_TileMode) {
	// For now, the easiest way to access the colors in the corners and sides is
	// to just make a bitmap from the image.
	if (!SkPDFUtils::ToBitmap(image, &bitmap)) {
	bitmap.allocN32Pixels(image->width(), image->height());
	bitmap.eraseColor(0x00000000);
	}
	}

	// If both x and y are in clamp mode, we start by filling in the corners.
	// (Which are just a rectangles of the corner colors.)
	if (tileModes[0] == SkShader::kClamp_TileMode &&
	tileModes[1] == SkShader::kClamp_TileMode) {
	SkASSERT(!bitmap.drawsNothing());
	SkPaint paint;
	SkRect rect;
	rect = SkRect::MakeLTRB(deviceBounds.left(), deviceBounds.top(), 0, 0);
	if (!rect.isEmpty()) {
	paint.setColor(bitmap.getColor(0, 0));
	canvas.drawRect(rect, paint);
	}

	rect = SkRect::MakeLTRB(width, deviceBounds.top(),
	deviceBounds.right(), 0);
	if (!rect.isEmpty()) {
	paint.setColor(bitmap.getColor(bitmap.width() - 1, 0));
	canvas.drawRect(rect, paint);
	}

	rect = SkRect::MakeLTRB(width, height,
	deviceBounds.right(), deviceBounds.bottom());
	if (!rect.isEmpty()) {
	paint.setColor(bitmap.getColor(bitmap.width() - 1,
	bitmap.height() - 1));
	canvas.drawRect(rect, paint);
	}

	rect = SkRect::MakeLTRB(deviceBounds.left(), height,
	0, deviceBounds.bottom());
	if (!rect.isEmpty()) {
	paint.setColor(bitmap.getColor(0, bitmap.height() - 1));
	canvas.drawRect(rect, paint);
	}
	}

	// Then expand the left, right, top, then bottom.
	if (tileModes[0] == SkShader::kClamp_TileMode) {
	SkASSERT(!bitmap.drawsNothing());
	SkIRect subset = SkIRect::MakeXYWH(0, 0, 1, bitmap.height());
	if (deviceBounds.left() < 0) {
	SkBitmap left;
	SkAssertResult(bitmap.extractSubset(&left, subset));

	SkMatrix leftMatrix;
	leftMatrix.setScale(-deviceBounds.left(), 1);
	leftMatrix.postTranslate(deviceBounds.left(), 0);
	draw_bitmap_matrix(&canvas, left, leftMatrix, paint);

	if (tileModes[1] == SkShader::kMirror_TileMode) {
	leftMatrix.postScale(SK_Scalar1, -SK_Scalar1);
	leftMatrix.postTranslate(0, 2 * height);
	draw_bitmap_matrix(&canvas, left, leftMatrix, paint);
	}
	patternBBox.fLeft = 0;
	}

	if (deviceBounds.right() > width) {
	SkBitmap right;
	subset.offset(bitmap.width() - 1, 0);
	SkAssertResult(bitmap.extractSubset(&right, subset));

	SkMatrix rightMatrix;
	rightMatrix.setScale(deviceBounds.right() - width, 1);
	rightMatrix.postTranslate(width, 0);
	draw_bitmap_matrix(&canvas, right, rightMatrix, paint);

	if (tileModes[1] == SkShader::kMirror_TileMode) {
	rightMatrix.postScale(SK_Scalar1, -SK_Scalar1);
	rightMatrix.postTranslate(0, 2 * height);
	draw_bitmap_matrix(&canvas, right, rightMatrix, paint);
	}
	patternBBox.fRight = deviceBounds.width();
	}
	}

	if (tileModes[1] == SkShader::kClamp_TileMode) {
	SkASSERT(!bitmap.drawsNothing());
	SkIRect subset = SkIRect::MakeXYWH(0, 0, bitmap.width(), 1);
	if (deviceBounds.top() < 0) {
	SkBitmap top;
	SkAssertResult(bitmap.extractSubset(&top, subset));

	SkMatrix topMatrix;
	topMatrix.setScale(SK_Scalar1, -deviceBounds.top());
	topMatrix.postTranslate(0, deviceBounds.top());
	draw_bitmap_matrix(&canvas, top, topMatrix, paint);

	if (tileModes[0] == SkShader::kMirror_TileMode) {
	topMatrix.postScale(-1, 1);
	topMatrix.postTranslate(2 * width, 0);
	draw_bitmap_matrix(&canvas, top, topMatrix, paint);
	}
	patternBBox.fTop = 0;
	}

	if (deviceBounds.bottom() > height) {
	SkBitmap bottom;
	subset.offset(0, bitmap.height() - 1);
	SkAssertResult(bitmap.extractSubset(&bottom, subset));

	SkMatrix bottomMatrix;
	bottomMatrix.setScale(SK_Scalar1, deviceBounds.bottom() - height);
	bottomMatrix.postTranslate(0, height);
	draw_bitmap_matrix(&canvas, bottom, bottomMatrix, paint);

	if (tileModes[0] == SkShader::kMirror_TileMode) {
	bottomMatrix.postScale(-1, 1);
	bottomMatrix.postTranslate(2 * width, 0);
	draw_bitmap_matrix(&canvas, bottom, bottomMatrix, paint);
	}
	patternBBox.fBottom = deviceBounds.height();
	}
	}

	auto imageShader = sk_make_sp<SkPDFStream>(patternDevice->content());
	sk_sp<SkPDFDict> resourceDict = patternDevice->makeResourceDict();
	SkPDFUtils::PopulateTilingPatternDict(imageShader->dict(), patternBBox,
	std::move(resourceDict), finalMatrix);
	return imageShader;
	}

	// Generic fallback for unsupported shaders:
	// * allocate a surfaceBBox-sized bitmap
	// * shade the whole area
	// * use the result as a bitmap shader
	static sk_sp<SkPDFObject> make_fallback_shader(SkPDFDocument* doc,
	SkShader* shader,
	const SkMatrix& canvasTransform,
	const SkIRect& surfaceBBox,
	SkColor paintColor) {
	// TODO(vandebo) This drops SKComposeShader on the floor. We could
	// handle compose shader by pulling things up to a layer, drawing with
	// the first shader, applying the xfer mode and drawing again with the
	// second shader, then applying the layer to the original drawing.
	SkPDFImageShaderKey key = {
	canvasTransform,
	SkMatrix::I(),
	surfaceBBox,
	{{0, 0, 0, 0}, 0}, // don't need the key; won't de-dup.
	{SkShader::kClamp_TileMode, SkShader::kClamp_TileMode},
	paintColor};

	key.fShaderTransform = shader->getLocalMatrix();

	// surfaceBBox is in device space. While that's exactly what we
	// want for sizing our bitmap, we need to map it into
	// shader space for adjustments (to match
	// MakeImageShader's behavior).
	SkRect shaderRect = SkRect::Make(surfaceBBox);
	if (!SkPDFUtils::InverseTransformBBox(canvasTransform, &shaderRect)) {
	return nullptr;
	}
	// Clamp the bitmap size to about 1M pixels
	static const SkScalar kMaxBitmapArea = 1024 * 1024;
	SkScalar bitmapArea = surfaceBBox.width() * surfaceBBox.height();
	SkScalar rasterScale = 1.0f;
	if (bitmapArea > kMaxBitmapArea) {
	rasterScale *= SkScalarSqrt(kMaxBitmapArea / bitmapArea);
	}

	SkISize size = {SkScalarRoundToInt(rasterScale * surfaceBBox.width()),
	SkScalarRoundToInt(rasterScale * surfaceBBox.height())};
	SkSize scale = {SkIntToScalar(size.width()) / shaderRect.width(),
	SkIntToScalar(size.height()) / shaderRect.height()};

	auto surface = SkSurface::MakeRasterN32Premul(size.width(), size.height());
	SkCanvas* canvas = surface->getCanvas();
	canvas->clear(SK_ColorTRANSPARENT);

	SkPaint p;
	p.setShader(sk_ref_sp(shader));
	p.setColor(paintColor);

	canvas->scale(scale.width(), scale.height());
	canvas->translate(-shaderRect.x(), -shaderRect.y());
	canvas->drawPaint(p);

	key.fShaderTransform.setTranslate(shaderRect.x(), shaderRect.y());
	key.fShaderTransform.preScale(1 / scale.width(), 1 / scale.height());

	sk_sp<SkImage> image = surface->makeImageSnapshot();
	return make_image_shader(doc, key, image.get());
	}

	static SkColor adjust_color(SkShader* shader, SkColor paintColor) {
	if (SkImage* img = shader->isAImage(nullptr, nullptr)) {
	if (img->isAlphaOnly()) {
	return paintColor;
	}
	}
	// only preserve the alpha.
	return paintColor & SK_ColorBLACK;
	}

	sk_sp<SkPDFObject> SkPDFMakeShader(SkPDFDocument* doc,
	SkShader* shader,
	const SkMatrix& canvasTransform,
	const SkIRect& surfaceBBox,
	SkColor paintColor) {
	SkASSERT(shader);
	SkASSERT(doc);
	if (SkShader::kNone_GradientType != shader->asAGradient(nullptr)) {
	return SkPDFGradientShader::Make(doc, shader, canvasTransform, surfaceBBox);
	}
	if (surfaceBBox.isEmpty()) {
	return nullptr;
	}
	SkBitmap image;
	SkPDFImageShaderKey key = {
	canvasTransform,
	SkMatrix::I(),
	surfaceBBox,
	{{0, 0, 0, 0}, 0},
	{SkShader::kClamp_TileMode, SkShader::kClamp_TileMode},
	adjust_color(shader, paintColor)};

	SkASSERT(shader->asAGradient(nullptr) == SkShader::kNone_GradientType) ;
	if (SkImage* skimg = shader->isAImage(&key.fShaderTransform, key.fImageTileModes)) {
	key.fBitmapKey = SkBitmapKeyFromImage(skimg);
	SkPDFCanon* canon = doc->canon();
	sk_sp<SkPDFObject>* shaderPtr = canon->fImageShaderMap.find(key);
	if (shaderPtr) {
	return *shaderPtr;
	}
	sk_sp<SkPDFObject> pdfShader = make_image_shader(doc, key, skimg);
	canon->fImageShaderMap.set(std::move(key), pdfShader);
	return pdfShader;
	}
	// Don't bother to de-dup fallback shader.
	return make_fallback_shader(doc, shader, canvasTransform, surfaceBBox, key.fPaintColor);
	}