add SkCanvas::NewRaster factory -- a very common use-case in chrome
BUG=skia:
R=scroggo@google.com
Author: reed@google.com
Review URL: https://codereview.chromium.org/183533004
git-svn-id: http://skia.googlecode.com/svn/trunk@13617 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index 8cc8bc9..b73a1e4 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -49,6 +49,35 @@
SK_DECLARE_INST_COUNT(SkCanvas)
/**
+ * Attempt to allocate an offscreen raster canvas, matching the ImageInfo.
+ * On success, return a new canvas that will draw into that offscreen.
+ *
+ * The caller can access the pixels after drawing into this canvas by
+ * calling readPixels() or peekPixels().
+ *
+ * If the requested ImageInfo is opaque (either the colortype is
+ * intrinsically opaque like RGB_565, or the info's alphatype is kOpaque)
+ * then the pixel memory may be uninitialized. Otherwise, the pixel memory
+ * will be initialized to 0, which is interpreted as transparent.
+ *
+ * On failure, return NULL. This can fail for several reasons:
+ * 1. the memory allocation failed (e.g. request is too large)
+ * 2. invalid ImageInfo (e.g. negative dimensions)
+ * 3. unsupported ImageInfo for a canvas
+ * - kUnknown_SkColorType, kIndex_8_SkColorType
+ * - kIgnore_SkAlphaType
+ * - this list is not complete, so others may also be unsupported
+ *
+ * Note: it is valid to request a supported ImageInfo, but with zero
+ * dimensions.
+ */
+ static SkCanvas* NewRaster(const SkImageInfo&);
+
+ static SkCanvas* NewRasterN32(int width, int height) {
+ return NewRaster(SkImageInfo::MakeN32Premul(width, height));
+ }
+
+ /**
* Creates an empty canvas with no backing device/pixels, and zero
* dimensions.
*/
diff --git a/src/core/SkCanvas.cpp b/src/core/SkCanvas.cpp
index a67891e..bc14974 100644
--- a/src/core/SkCanvas.cpp
+++ b/src/core/SkCanvas.cpp
@@ -2314,3 +2314,43 @@
///////////////////////////////////////////////////////////////////////////////
SkCanvas::ClipVisitor::~ClipVisitor() { }
+
+///////////////////////////////////////////////////////////////////////////////
+
+static bool supported_for_raster_canvas(const SkImageInfo& info) {
+ switch (info.alphaType()) {
+ case kPremul_SkAlphaType:
+ case kOpaque_SkAlphaType:
+ break;
+ default:
+ return false;
+ }
+
+ switch (info.colorType()) {
+ case kAlpha_8_SkColorType:
+ case kRGB_565_SkColorType:
+ case kPMColor_SkColorType:
+ break;
+ default:
+ return false;
+ }
+
+ return true;
+}
+
+SkCanvas* SkCanvas::NewRaster(const SkImageInfo& info) {
+ if (!supported_for_raster_canvas(info)) {
+ return NULL;
+ }
+
+ SkBitmap bitmap;
+ if (!bitmap.allocPixels(info)) {
+ return NULL;
+ }
+
+ // should this functionality be moved into allocPixels()?
+ if (!bitmap.info().isOpaque()) {
+ bitmap.eraseColor(0);
+ }
+ return SkNEW_ARGS(SkCanvas, (bitmap));
+}
diff --git a/tests/CanvasTest.cpp b/tests/CanvasTest.cpp
index 5f3d79c..18c683d 100644
--- a/tests/CanvasTest.cpp
+++ b/tests/CanvasTest.cpp
@@ -1,4 +1,3 @@
-
/*
* Copyright 2012 Google Inc.
*
@@ -893,6 +892,45 @@
}
}
+static void test_newraster(skiatest::Reporter* reporter) {
+ SkImageInfo info = SkImageInfo::MakeN32Premul(10, 10);
+ SkCanvas* canvas = SkCanvas::NewRaster(info);
+ REPORTER_ASSERT(reporter, canvas);
+
+ SkImageInfo info2;
+ size_t rowBytes;
+ const SkPMColor* addr = (const SkPMColor*)canvas->peekPixels(&info2, &rowBytes);
+ REPORTER_ASSERT(reporter, addr);
+ REPORTER_ASSERT(reporter, info == info2);
+ for (int y = 0; y < info.height(); ++y) {
+ for (int x = 0; x < info.width(); ++x) {
+ REPORTER_ASSERT(reporter, 0 == addr[x]);
+ }
+ addr = (const SkPMColor*)((const char*)addr + rowBytes);
+ }
+ SkDELETE(canvas);
+
+ // now try a deliberately bad info
+ info.fWidth = -1;
+ REPORTER_ASSERT(reporter, NULL == SkCanvas::NewRaster(info));
+
+ // too big
+ info.fWidth = 1 << 30;
+ info.fHeight = 1 << 30;
+ REPORTER_ASSERT(reporter, NULL == SkCanvas::NewRaster(info));
+
+ // not a valid pixel type
+ info.fWidth = info.fHeight = 10;
+ info.fColorType = kUnknown_SkColorType;
+ REPORTER_ASSERT(reporter, NULL == SkCanvas::NewRaster(info));
+
+ // We should succeed with a zero-sized valid info
+ info = SkImageInfo::MakeN32Premul(0, 0);
+ canvas = SkCanvas::NewRaster(info);
+ REPORTER_ASSERT(reporter, canvas);
+ SkDELETE(canvas);
+}
+
DEF_TEST(Canvas, reporter) {
// Init global here because bitmap pixels cannot be alocated during
// static initialization
@@ -909,4 +947,6 @@
// Explicitly call reset(), so we don't leak the pixels (since kTestBitmap is a global)
kTestBitmap.reset();
+
+ test_newraster(reporter);
}
diff --git a/tests/DrawPathTest.cpp b/tests/DrawPathTest.cpp
index f7f7367..fafef02 100644
--- a/tests/DrawPathTest.cpp
+++ b/tests/DrawPathTest.cpp
@@ -11,14 +11,6 @@
#include "SkSurface.h"
#include "Test.h"
-static SkCanvas* new_canvas(int w, int h) {
- SkBitmap bm;
- bm.allocN32Pixels(w, h);
- return new SkCanvas(bm);
-}
-
-///////////////////////////////////////////////////////////////////////////////
-
// test that we can draw an aa-rect at coordinates > 32K (bigger than fixedpoint)
static void test_big_aa_rect(skiatest::Reporter* reporter) {
SkBitmap output;
@@ -103,7 +95,7 @@
moveToH(&path, &data[0]);
cubicToH(&path, &data[2]);
- SkAutoTUnref<SkCanvas> canvas(new_canvas(640, 480));
+ SkAutoTUnref<SkCanvas> canvas(SkCanvas::NewRasterN32(640, 480));
SkPaint paint;
paint.setAntiAlias(true);
@@ -141,7 +133,7 @@
SkPaint paint;
- SkAutoTUnref<SkCanvas> canvas(new_canvas(640, 480));
+ SkAutoTUnref<SkCanvas> canvas(SkCanvas::NewRasterN32(640, 480));
canvas.get()->save();
canvas.get()->clipRect(SkRect::MakeWH(SkIntToScalar(19), SkIntToScalar(11)));
@@ -181,7 +173,7 @@
SkPaint paint;
paint.setAntiAlias(true);
- SkAutoTUnref<SkCanvas> canvas(new_canvas(640, 480));
+ SkAutoTUnref<SkCanvas> canvas(SkCanvas::NewRasterN32(640, 480));
canvas.get()->drawPath(path, paint);
}
@@ -223,7 +215,7 @@
SkPaint paint;
paint.setAntiAlias(true);
- SkAutoTUnref<SkCanvas> canvas(new_canvas(640, 480));
+ SkAutoTUnref<SkCanvas> canvas(SkCanvas::NewRasterN32(640, 480));
canvas.get()->drawPath(path, paint);
}
@@ -233,8 +225,7 @@
static void test_giantaa() {
const int W = 400;
const int H = 400;
- SkAutoTUnref<SkCanvas> canvas(new_canvas(33000, 10));
- canvas.get()->clear(SK_ColorTRANSPARENT);
+ SkAutoTUnref<SkCanvas> canvas(SkCanvas::NewRasterN32(33000, 10));
SkPaint paint;
paint.setAntiAlias(true);