scaling API on SkPixmap

gm/image.cpp

Index: gm/image.cpp
diff --git a/gm/image.cpp b/gm/image.cpp
index 27cce2342e24a10ffddb13b3f61c036170de7433..03ed1059cf33298901f181cbd9401b4b5b309899 100644
--- a/gm/image.cpp
+++ b/gm/image.cpp
@@ -192,3 +192,111 @@ private:
     typedef skiagm::GM INHERITED;
 };
 DEF_GM( return new ImageGM; )
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+#include "SkPictureRecorder.h"
+
+static void draw_pixmap(SkCanvas* canvas, const SkPixmap& pmap) {
+    SkBitmap bitmap;
+    bitmap.installPixels(pmap.info(), (void*)pmap.addr(), pmap.rowBytes());
+    canvas->drawBitmap(bitmap, 0, 0, nullptr);
+}
+
+static void show_scaled_pixels(SkCanvas* canvas, SkImage* image) {
+    SkAutoCanvasRestore acr(canvas, true);
+
+    canvas->drawImage(image, 0, 0, nullptr);
+    canvas->translate(110, 10);
+
+    const SkImageInfo info = SkImageInfo::MakeN32Premul(40, 40);
+    SkAutoPixmapStorage storage;
+    storage.alloc(info);
+
+    const SkImage::CachingHint chints[] = {
+        SkImage::kAllow_CachingHint, // SkImage::kDisallow_CachingHint,
+    };
+    const SkFilterQuality qualities[] = {
+        kNone_SkFilterQuality, kLow_SkFilterQuality, kMedium_SkFilterQuality, kHigh_SkFilterQuality,
+    };
+
+    for (auto ch : chints) {
+        canvas->save();
+        for (auto q : qualities) {
+            if (image->scalePixels(storage, q, ch)) {
+                draw_pixmap(canvas, storage);
+            }
+            canvas->translate(70, 0);
+        }
+        canvas->restore();
+        canvas->translate(0, 45);
+    }
+}
+
+static void draw_contents(SkCanvas* canvas) {
+    SkPaint paint;
+    paint.setStyle(SkPaint::kStroke_Style);
+    paint.setStrokeWidth(20);
+    canvas->drawCircle(50, 50, 35, paint);
+}
+
+static SkImage* make_raster(const SkImageInfo& info, GrContext*) {
+    SkAutoTUnref<SkSurface> surface(SkSurface::NewRaster(info));
+    draw_contents(surface->getCanvas());
+    return surface->newImageSnapshot();
+}
+
+static SkImage* make_picture(const SkImageInfo& info, GrContext*) {
+    SkPictureRecorder recorder;
+    draw_contents(recorder.beginRecording(SkRect::MakeIWH(info.width(), info.height())));
+    SkAutoTUnref<SkPicture> pict(recorder.endRecording());
+    return SkImage::NewFromPicture(pict, info.dimensions(), nullptr, nullptr);
+}
+
+static SkImage* make_codec(const SkImageInfo& info, GrContext*) {
+    SkAutoTUnref<SkImage> image(make_raster(info, nullptr));
+    SkAutoTUnref<SkData> data(image->encode());
+    return SkImage::NewFromEncoded(data);
+}
+
+static SkImage* make_gpu(const SkImageInfo& info, GrContext* ctx) {
+    if (!ctx) { return nullptr; }
+    SkAutoTUnref<SkSurface> surface(SkSurface::NewRenderTarget(ctx, SkSurface::kNo_Budgeted, info));
+    draw_contents(surface->getCanvas());
+    return surface->newImageSnapshot();
+}
+
+typedef SkImage* (*ImageMakerProc)(const SkImageInfo&, GrContext*);
+
+class ScalePixelsGM : public skiagm::GM {
+public:
+    ScalePixelsGM() {}
+
+protected:
+    SkString onShortName() override {
+        return SkString("scale-pixels");
+    }
+
+    SkISize onISize() override {
+        return SkISize::Make(960, 1200);
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        const SkImageInfo info = SkImageInfo::MakeN32Premul(100, 100);
+
+        const ImageMakerProc procs[] = {
+            make_raster, make_picture, make_codec, make_gpu,
+        };
+        for (auto& proc : procs) {
+            SkAutoTUnref<SkImage> image(proc(info, canvas->getGrContext()));
+            if (image) {
+                show_scaled_pixels(canvas, image);
+            }
+            canvas->translate(0, 120);
+        }
+    }
+    
+private:
+    typedef skiagm::GM INHERITED;
+};
+DEF_GM( return new ScalePixelsGM; )