src/utils/SkNinePatch.cpp - platform/external/skqp - Gitiles


 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */


 #include "SkNinePatch.h"
 #include "SkCanvas.h"
 #include "SkShader.h"

 static const uint16_t g3x3Indices[] = {
     0, 5, 1,    0, 4, 5,
     1, 6, 2,    1, 5, 6,
     2, 7, 3,    2, 6, 7,

     4, 9, 5,    4, 8, 9,
     5, 10, 6,   5, 9, 10,
     6, 11, 7,   6, 10, 11,

     8, 13, 9,   8, 12, 13,
     9, 14, 10,  9, 13, 14,
     10, 15, 11, 10, 14, 15
 };

 static int fillIndices(uint16_t indices[], int xCount, int yCount) {
     uint16_t* startIndices = indices;

     int n = 0;
     for (int y = 0; y < yCount; y++) {
         for (int x = 0; x < xCount; x++) {
             *indices++ = n;
             *indices++ = n + xCount + 2;
             *indices++ = n + 1;

             *indices++ = n;
             *indices++ = n + xCount + 1;
             *indices++ = n + xCount + 2;

             n += 1;
         }
         n += 1;
     }
     return static_cast<int>(indices - startIndices);
 }

 // Computes the delta between vertices along a single axis
 static SkScalar computeVertexDelta(bool isStretchyVertex,
                                    SkScalar currentVertex,
                                    SkScalar prevVertex,
                                    SkScalar stretchFactor) {
     // the standard delta between vertices if no stretching is required
     SkScalar delta = currentVertex - prevVertex;

     // if the stretch factor is negative or zero we need to shrink the 9-patch
     // to fit within the target bounds.  This means that we will eliminate all
     // stretchy areas and scale the fixed areas to fit within the target bounds.
     if (stretchFactor <= 0) {
         if (isStretchyVertex)
             delta = 0; // collapse stretchable areas
         else
             delta = SkScalarMul(delta, -stretchFactor); // scale fixed areas
     // if the stretch factor is positive then we use the standard delta for
     // fixed and scale the stretchable areas to fill the target bounds.
     } else if (isStretchyVertex) {
         delta = SkScalarMul(delta, stretchFactor);
     }

     return delta;
 }

 static void fillRow(SkPoint verts[], SkPoint texs[],
                     const SkScalar vy, const SkScalar ty,
                     const SkRect& bounds, const int32_t xDivs[], int numXDivs,
                     const SkScalar stretchX, int width) {
     SkScalar vx = bounds.fLeft;
     verts->set(vx, vy); verts++;
     texs->set(0, ty); texs++;

     SkScalar prev = 0;
     for (int x = 0; x < numXDivs; x++) {

         const SkScalar tx = SkIntToScalar(xDivs[x]);
         vx += computeVertexDelta(x & 1, tx, prev, stretchX);
         prev = tx;

         verts->set(vx, vy); verts++;
         texs->set(tx, ty); texs++;
     }
     verts->set(bounds.fRight, vy); verts++;
     texs->set(SkIntToScalar(width), ty); texs++;
 }

 struct Mesh {
     const SkPoint*  fVerts;
     const SkPoint*  fTexs;
     const SkColor*  fColors;
     const uint16_t* fIndices;
 };

 void SkNinePatch::DrawMesh(SkCanvas* canvas, const SkRect& bounds,
                            const SkBitmap& bitmap,
                            const int32_t xDivs[], int numXDivs,
                            const int32_t yDivs[], int numYDivs,
                            const SkPaint* paint) {
     if (bounds.isEmpty() || bitmap.width() == 0 || bitmap.height() == 0) {
         return;
     }

     // should try a quick-reject test before calling lockPixels
     SkAutoLockPixels alp(bitmap);
     // after the lock, it is valid to check
     if (!bitmap.readyToDraw()) {
         return;
     }

     // check for degenerate divs (just an optimization, not required)
     {
         int i;
         int zeros = 0;
         for (i = 0; i < numYDivs && yDivs[i] == 0; i++) {
             zeros += 1;
         }
         numYDivs -= zeros;
         yDivs += zeros;
         for (i = numYDivs - 1; i >= 0 && yDivs[i] == bitmap.height(); --i) {
             numYDivs -= 1;
         }
     }

     Mesh mesh;

     const int numXStretch = (numXDivs + 1) >> 1;
     const int numYStretch = (numYDivs + 1) >> 1;

     if (numXStretch < 1 && numYStretch < 1) {
         canvas->drawBitmapRect(bitmap, NULL, bounds, paint);
         return;
     }

     if (false) {
         int i;
         for (i = 0; i < numXDivs; i++) {
             SkDebugf("--- xdivs[%d] %d\n", i, xDivs[i]);
         }
         for (i = 0; i < numYDivs; i++) {
             SkDebugf("--- ydivs[%d] %d\n", i, yDivs[i]);
         }
     }

     SkScalar stretchX = 0, stretchY = 0;

     if (numXStretch > 0) {
         int stretchSize = 0;
         for (int i = 1; i < numXDivs; i += 2) {
             stretchSize += xDivs[i] - xDivs[i-1];
         }
         const SkScalar fixed = SkIntToScalar(bitmap.width() - stretchSize);
         if (bounds.width() >= fixed)
             stretchX = (bounds.width() - fixed) / stretchSize;
         else // reuse stretchX, but keep it negative as a signal
             stretchX = -bounds.width() / fixed;
     }

     if (numYStretch > 0) {
         int stretchSize = 0;
         for (int i = 1; i < numYDivs; i += 2) {
             stretchSize += yDivs[i] - yDivs[i-1];
         }
         const SkScalar fixed = SkIntToScalar(bitmap.height() - stretchSize);
         if (bounds.height() >= fixed)
             stretchY = (bounds.height() - fixed) / stretchSize;
         else // reuse stretchX, but keep it negative as a signal
             stretchY = -bounds.height() / fixed;
     }

 #if 0
     SkDebugf("---- drawasamesh [%d %d] -> [%g %g] <%d %d> (%g %g)\n",
              bitmap.width(), bitmap.height(),
              SkScalarToFloat(bounds.width()), SkScalarToFloat(bounds.height()),
              numXDivs + 1, numYDivs + 1,
              SkScalarToFloat(stretchX), SkScalarToFloat(stretchY));
 #endif

     const int vCount = (numXDivs + 2) * (numYDivs + 2);
     // number of celss * 2 (tris per cell) * 3 (verts per tri)
     const int indexCount = (numXDivs + 1) * (numYDivs + 1) * 2 * 3;
     // allocate 2 times, one for verts, one for texs, plus indices
     SkAutoMalloc storage(vCount * sizeof(SkPoint) * 2 +
                          indexCount * sizeof(uint16_t));
     SkPoint* verts = (SkPoint*)storage.get();
     SkPoint* texs = verts + vCount;
     uint16_t* indices = (uint16_t*)(texs + vCount);

     mesh.fVerts = verts;
     mesh.fTexs = texs;
     mesh.fColors = NULL;
     mesh.fIndices = NULL;

     // we use <= for YDivs, since the prebuild indices work for 3x2 and 3x1 too
     if (numXDivs == 2 && numYDivs <= 2) {
         mesh.fIndices = g3x3Indices;
     } else {
         SkDEBUGCODE(int n =) fillIndices(indices, numXDivs + 1, numYDivs + 1);
         SkASSERT(n == indexCount);
         mesh.fIndices = indices;
     }

     SkScalar vy = bounds.fTop;
     fillRow(verts, texs, vy, 0, bounds, xDivs, numXDivs,
             stretchX, bitmap.width());
     verts += numXDivs + 2;
     texs += numXDivs + 2;
     for (int y = 0; y < numYDivs; y++) {
         const SkScalar ty = SkIntToScalar(yDivs[y]);
         if (stretchY >= 0) {
             if (y & 1) {
                 vy += stretchY;
             } else {
                 vy += ty;
             }
         } else {    // shrink fixed sections, and collaps stretchy sections
             if (y & 1) {
                 ;// do nothing
             } else {
                 vy += SkScalarMul(ty, -stretchY);
             }
         }
         fillRow(verts, texs, vy, ty, bounds, xDivs, numXDivs,
                 stretchX, bitmap.width());
         verts += numXDivs + 2;
         texs += numXDivs + 2;
     }
     fillRow(verts, texs, bounds.fBottom, SkIntToScalar(bitmap.height()),
             bounds, xDivs, numXDivs, stretchX, bitmap.width());

     SkShader* shader = SkShader::CreateBitmapShader(bitmap,
                                                     SkShader::kClamp_TileMode,
                                                     SkShader::kClamp_TileMode);
     SkPaint p;
     if (paint) {
         p = *paint;
     }
     p.setShader(shader)->unref();
     canvas->drawVertices(SkCanvas::kTriangles_VertexMode, vCount,
                          mesh.fVerts, mesh.fTexs, mesh.fColors, NULL,
                          mesh.fIndices, indexCount, p);
 }

 ///////////////////////////////////////////////////////////////////////////////

 static void drawNineViaRects(SkCanvas* canvas, const SkRect& dst,
                              const SkBitmap& bitmap, const SkIRect& margins,
                              const SkPaint* paint) {
     const int32_t srcX[4] = {
         0, margins.fLeft, bitmap.width() - margins.fRight, bitmap.width()
     };
     const int32_t srcY[4] = {
         0, margins.fTop, bitmap.height() - margins.fBottom, bitmap.height()
     };
     SkScalar dstX[4] = {
         dst.fLeft, dst.fLeft + SkIntToScalar(margins.fLeft),
         dst.fRight - SkIntToScalar(margins.fRight), dst.fRight
     };
     SkScalar dstY[4] = {
         dst.fTop, dst.fTop + SkIntToScalar(margins.fTop),
         dst.fBottom - SkIntToScalar(margins.fBottom), dst.fBottom
     };

     if (dstX[1] > dstX[2]) {
         dstX[1] = dstX[0] + (dstX[3] - dstX[0]) * SkIntToScalar(margins.fLeft) /
             (SkIntToScalar(margins.fLeft) + SkIntToScalar(margins.fRight));
         dstX[2] = dstX[1];
     }

     if (dstY[1] > dstY[2]) {
         dstY[1] = dstY[0] + (dstY[3] - dstY[0]) * SkIntToScalar(margins.fTop) /
             (SkIntToScalar(margins.fTop) + SkIntToScalar(margins.fBottom));
         dstY[2] = dstY[1];
     }

     SkIRect s;
     SkRect  d;
     for (int y = 0; y < 3; y++) {
         s.fTop = srcY[y];
         s.fBottom = srcY[y+1];
         d.fTop = dstY[y];
         d.fBottom = dstY[y+1];
         for (int x = 0; x < 3; x++) {
             s.fLeft = srcX[x];
             s.fRight = srcX[x+1];
             d.fLeft = dstX[x];
             d.fRight = dstX[x+1];
             canvas->drawBitmapRect(bitmap, &s, d, paint);
         }
     }
 }

 void SkNinePatch::DrawNine(SkCanvas* canvas, const SkRect& bounds,
                            const SkBitmap& bitmap, const SkIRect& margins,
                            const SkPaint* paint) {
     /** Our vertices code has numerical precision problems if the transformed
      coordinates land directly on a 1/2 pixel boundary. To work around that
      for now, we only take the vertices case if we are in opengl. Also,
      when not in GL, the vertices impl is slower (more math) than calling
      the viaRects code.
      */
     if (false /* is our canvas backed by a gpu?*/) {
         int32_t xDivs[2];
         int32_t yDivs[2];

         xDivs[0] = margins.fLeft;
         xDivs[1] = bitmap.width() - margins.fRight;
         yDivs[0] = margins.fTop;
         yDivs[1] = bitmap.height() - margins.fBottom;

         if (xDivs[0] > xDivs[1]) {
             xDivs[0] = bitmap.width() * margins.fLeft /
                 (margins.fLeft + margins.fRight);
             xDivs[1] = xDivs[0];
         }
         if (yDivs[0] > yDivs[1]) {
             yDivs[0] = bitmap.height() * margins.fTop /
                 (margins.fTop + margins.fBottom);
             yDivs[1] = yDivs[0];
         }

         SkNinePatch::DrawMesh(canvas, bounds, bitmap,
                               xDivs, 2, yDivs, 2, paint);
     } else {
         drawNineViaRects(canvas, bounds, bitmap, margins, paint);
     }
 }

	/*
	* Copyright 2006 The Android Open Source Project
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/


	#include "SkNinePatch.h"
	#include "SkCanvas.h"
	#include "SkShader.h"

	static const uint16_t g3x3Indices[] = {
	0, 5, 1, 0, 4, 5,
	1, 6, 2, 1, 5, 6,
	2, 7, 3, 2, 6, 7,

	4, 9, 5, 4, 8, 9,
	5, 10, 6, 5, 9, 10,
	6, 11, 7, 6, 10, 11,

	8, 13, 9, 8, 12, 13,
	9, 14, 10, 9, 13, 14,
	10, 15, 11, 10, 14, 15
	};

	static int fillIndices(uint16_t indices[], int xCount, int yCount) {
	uint16_t* startIndices = indices;

	int n = 0;
	for (int y = 0; y < yCount; y++) {
	for (int x = 0; x < xCount; x++) {
	*indices++ = n;
	*indices++ = n + xCount + 2;
	*indices++ = n + 1;

	*indices++ = n;
	*indices++ = n + xCount + 1;
	*indices++ = n + xCount + 2;

	n += 1;
	}
	n += 1;
	}
	return static_cast<int>(indices - startIndices);
	}

	// Computes the delta between vertices along a single axis
	static SkScalar computeVertexDelta(bool isStretchyVertex,
	SkScalar currentVertex,
	SkScalar prevVertex,
	SkScalar stretchFactor) {
	// the standard delta between vertices if no stretching is required
	SkScalar delta = currentVertex - prevVertex;

	// if the stretch factor is negative or zero we need to shrink the 9-patch
	// to fit within the target bounds. This means that we will eliminate all
	// stretchy areas and scale the fixed areas to fit within the target bounds.
	if (stretchFactor <= 0) {
	if (isStretchyVertex)
	delta = 0; // collapse stretchable areas
	else
	delta = SkScalarMul(delta, -stretchFactor); // scale fixed areas
	// if the stretch factor is positive then we use the standard delta for
	// fixed and scale the stretchable areas to fill the target bounds.
	} else if (isStretchyVertex) {
	delta = SkScalarMul(delta, stretchFactor);
	}

	return delta;
	}

	static void fillRow(SkPoint verts[], SkPoint texs[],
	const SkScalar vy, const SkScalar ty,
	const SkRect& bounds, const int32_t xDivs[], int numXDivs,
	const SkScalar stretchX, int width) {
	SkScalar vx = bounds.fLeft;
	verts->set(vx, vy); verts++;
	texs->set(0, ty); texs++;

	SkScalar prev = 0;
	for (int x = 0; x < numXDivs; x++) {

	const SkScalar tx = SkIntToScalar(xDivs[x]);
	vx += computeVertexDelta(x & 1, tx, prev, stretchX);
	prev = tx;

	verts->set(vx, vy); verts++;
	texs->set(tx, ty); texs++;
	}
	verts->set(bounds.fRight, vy); verts++;
	texs->set(SkIntToScalar(width), ty); texs++;
	}

	struct Mesh {
	const SkPoint* fVerts;
	const SkPoint* fTexs;
	const SkColor* fColors;
	const uint16_t* fIndices;
	};

	void SkNinePatch::DrawMesh(SkCanvas* canvas, const SkRect& bounds,
	const SkBitmap& bitmap,
	const int32_t xDivs[], int numXDivs,
	const int32_t yDivs[], int numYDivs,
	const SkPaint* paint) {
	if (bounds.isEmpty() \|\| bitmap.width() == 0 \|\| bitmap.height() == 0) {
	return;
	}

	// should try a quick-reject test before calling lockPixels
	SkAutoLockPixels alp(bitmap);
	// after the lock, it is valid to check
	if (!bitmap.readyToDraw()) {
	return;
	}

	// check for degenerate divs (just an optimization, not required)
	{
	int i;
	int zeros = 0;
	for (i = 0; i < numYDivs && yDivs[i] == 0; i++) {
	zeros += 1;
	}
	numYDivs -= zeros;
	yDivs += zeros;
	for (i = numYDivs - 1; i >= 0 && yDivs[i] == bitmap.height(); --i) {
	numYDivs -= 1;
	}
	}

	Mesh mesh;

	const int numXStretch = (numXDivs + 1) >> 1;
	const int numYStretch = (numYDivs + 1) >> 1;

	if (numXStretch < 1 && numYStretch < 1) {
	canvas->drawBitmapRect(bitmap, NULL, bounds, paint);
	return;
	}

	if (false) {
	int i;
	for (i = 0; i < numXDivs; i++) {
	SkDebugf("--- xdivs[%d] %d\n", i, xDivs[i]);
	}
	for (i = 0; i < numYDivs; i++) {
	SkDebugf("--- ydivs[%d] %d\n", i, yDivs[i]);
	}
	}

	SkScalar stretchX = 0, stretchY = 0;

	if (numXStretch > 0) {
	int stretchSize = 0;
	for (int i = 1; i < numXDivs; i += 2) {
	stretchSize += xDivs[i] - xDivs[i-1];
	}
	const SkScalar fixed = SkIntToScalar(bitmap.width() - stretchSize);
	if (bounds.width() >= fixed)
	stretchX = (bounds.width() - fixed) / stretchSize;
	else // reuse stretchX, but keep it negative as a signal
	stretchX = -bounds.width() / fixed;
	}

	if (numYStretch > 0) {
	int stretchSize = 0;
	for (int i = 1; i < numYDivs; i += 2) {
	stretchSize += yDivs[i] - yDivs[i-1];
	}
	const SkScalar fixed = SkIntToScalar(bitmap.height() - stretchSize);
	if (bounds.height() >= fixed)
	stretchY = (bounds.height() - fixed) / stretchSize;
	else // reuse stretchX, but keep it negative as a signal
	stretchY = -bounds.height() / fixed;
	}

	#if 0
	SkDebugf("---- drawasamesh [%d %d] -> [%g %g] <%d %d> (%g %g)\n",
	bitmap.width(), bitmap.height(),
	SkScalarToFloat(bounds.width()), SkScalarToFloat(bounds.height()),
	numXDivs + 1, numYDivs + 1,
	SkScalarToFloat(stretchX), SkScalarToFloat(stretchY));
	#endif

	const int vCount = (numXDivs + 2) * (numYDivs + 2);
	// number of celss * 2 (tris per cell) * 3 (verts per tri)
	const int indexCount = (numXDivs + 1) * (numYDivs + 1) * 2 * 3;
	// allocate 2 times, one for verts, one for texs, plus indices
	SkAutoMalloc storage(vCount * sizeof(SkPoint) * 2 +
	indexCount * sizeof(uint16_t));
	SkPoint* verts = (SkPoint*)storage.get();
	SkPoint* texs = verts + vCount;
	uint16_t* indices = (uint16_t*)(texs + vCount);

	mesh.fVerts = verts;
	mesh.fTexs = texs;
	mesh.fColors = NULL;
	mesh.fIndices = NULL;

	// we use <= for YDivs, since the prebuild indices work for 3x2 and 3x1 too
	if (numXDivs == 2 && numYDivs <= 2) {
	mesh.fIndices = g3x3Indices;
	} else {
	SkDEBUGCODE(int n =) fillIndices(indices, numXDivs + 1, numYDivs + 1);
	SkASSERT(n == indexCount);
	mesh.fIndices = indices;
	}

	SkScalar vy = bounds.fTop;
	fillRow(verts, texs, vy, 0, bounds, xDivs, numXDivs,
	stretchX, bitmap.width());
	verts += numXDivs + 2;
	texs += numXDivs + 2;
	for (int y = 0; y < numYDivs; y++) {
	const SkScalar ty = SkIntToScalar(yDivs[y]);
	if (stretchY >= 0) {
	if (y & 1) {
	vy += stretchY;
	} else {
	vy += ty;
	}
	} else { // shrink fixed sections, and collaps stretchy sections
	if (y & 1) {
	;// do nothing
	} else {
	vy += SkScalarMul(ty, -stretchY);
	}
	}
	fillRow(verts, texs, vy, ty, bounds, xDivs, numXDivs,
	stretchX, bitmap.width());
	verts += numXDivs + 2;
	texs += numXDivs + 2;
	}
	fillRow(verts, texs, bounds.fBottom, SkIntToScalar(bitmap.height()),
	bounds, xDivs, numXDivs, stretchX, bitmap.width());

	SkShader* shader = SkShader::CreateBitmapShader(bitmap,
	SkShader::kClamp_TileMode,
	SkShader::kClamp_TileMode);
	SkPaint p;
	if (paint) {
	p = *paint;
	}
	p.setShader(shader)->unref();
	canvas->drawVertices(SkCanvas::kTriangles_VertexMode, vCount,
	mesh.fVerts, mesh.fTexs, mesh.fColors, NULL,
	mesh.fIndices, indexCount, p);
	}

	///////////////////////////////////////////////////////////////////////////////

	static void drawNineViaRects(SkCanvas* canvas, const SkRect& dst,
	const SkBitmap& bitmap, const SkIRect& margins,
	const SkPaint* paint) {
	const int32_t srcX[4] = {
	0, margins.fLeft, bitmap.width() - margins.fRight, bitmap.width()
	};
	const int32_t srcY[4] = {
	0, margins.fTop, bitmap.height() - margins.fBottom, bitmap.height()
	};
	SkScalar dstX[4] = {
	dst.fLeft, dst.fLeft + SkIntToScalar(margins.fLeft),
	dst.fRight - SkIntToScalar(margins.fRight), dst.fRight
	};
	SkScalar dstY[4] = {
	dst.fTop, dst.fTop + SkIntToScalar(margins.fTop),
	dst.fBottom - SkIntToScalar(margins.fBottom), dst.fBottom
	};

	if (dstX[1] > dstX[2]) {
	dstX[1] = dstX[0] + (dstX[3] - dstX[0]) * SkIntToScalar(margins.fLeft) /
	(SkIntToScalar(margins.fLeft) + SkIntToScalar(margins.fRight));
	dstX[2] = dstX[1];
	}

	if (dstY[1] > dstY[2]) {
	dstY[1] = dstY[0] + (dstY[3] - dstY[0]) * SkIntToScalar(margins.fTop) /
	(SkIntToScalar(margins.fTop) + SkIntToScalar(margins.fBottom));
	dstY[2] = dstY[1];
	}

	SkIRect s;
	SkRect d;
	for (int y = 0; y < 3; y++) {
	s.fTop = srcY[y];
	s.fBottom = srcY[y+1];
	d.fTop = dstY[y];
	d.fBottom = dstY[y+1];
	for (int x = 0; x < 3; x++) {
	s.fLeft = srcX[x];
	s.fRight = srcX[x+1];
	d.fLeft = dstX[x];
	d.fRight = dstX[x+1];
	canvas->drawBitmapRect(bitmap, &s, d, paint);
	}
	}
	}

	void SkNinePatch::DrawNine(SkCanvas* canvas, const SkRect& bounds,
	const SkBitmap& bitmap, const SkIRect& margins,
	const SkPaint* paint) {
	/** Our vertices code has numerical precision problems if the transformed
	coordinates land directly on a 1/2 pixel boundary. To work around that
	for now, we only take the vertices case if we are in opengl. Also,
	when not in GL, the vertices impl is slower (more math) than calling
	the viaRects code.
	*/
	if (false /* is our canvas backed by a gpu?*/) {
	int32_t xDivs[2];
	int32_t yDivs[2];

	xDivs[0] = margins.fLeft;
	xDivs[1] = bitmap.width() - margins.fRight;
	yDivs[0] = margins.fTop;
	yDivs[1] = bitmap.height() - margins.fBottom;

	if (xDivs[0] > xDivs[1]) {
	xDivs[0] = bitmap.width() * margins.fLeft /
	(margins.fLeft + margins.fRight);
	xDivs[1] = xDivs[0];
	}
	if (yDivs[0] > yDivs[1]) {
	yDivs[0] = bitmap.height() * margins.fTop /
	(margins.fTop + margins.fBottom);
	yDivs[1] = yDivs[0];
	}

	SkNinePatch::DrawMesh(canvas, bounds, bitmap,
	xDivs, 2, yDivs, 2, paint);
	} else {
	drawNineViaRects(canvas, bounds, bitmap, margins, paint);
	}
	}