support colortables in cacherator

gm/image_pict.cpp

Index: gm/image_pict.cpp
diff --git a/gm/image_pict.cpp b/gm/image_pict.cpp
index 22b3d0067b888ca6e38e0ac5ab42b1bcd2405071..216b495dd3580785cb40f19ecf304798404a4e90 100644
--- a/gm/image_pict.cpp
+++ b/gm/image_pict.cpp
@@ -108,11 +108,35 @@ static SkImageGenerator* make_pic_generator(GrContext*, SkPicture* pic) {
 
 class RasterGenerator : public SkImageGenerator {
 public:
-    RasterGenerator(const SkBitmap& bm) : SkImageGenerator(bm.info()), fBM(bm) {}
+    RasterGenerator(const SkBitmap& bm) : SkImageGenerator(bm.info()), fBM(bm) {
+        fBM.lockPixels();
+    }
 protected:
     bool onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
-                     SkPMColor*, int*) override {
-        return fBM.readPixels(info, pixels, rowBytes, 0, 0);
+                     SkPMColor* ctable, int* ctableCount) override {
+        SkASSERT(fBM.width() == info.width());
+        SkASSERT(fBM.height() == info.height());
+
+        if (info.colorType() == kIndex_8_SkColorType) {
+            if (SkColorTable* ct = fBM.getColorTable()) {
+                if (ctable) {
+                    memcpy(ctable, ct->readColors(), ct->count() * sizeof(SkPMColor));
+                }
+                if (ctableCount) {
+                    *ctableCount = ct->count();
+                }
+
+                for (int y = 0; y < info.height(); ++y) {
+                    memcpy(pixels, fBM.getAddr8(0, y), fBM.width());
+                    pixels = (char*)pixels + rowBytes;
+                }
+                return true;
+            } else {
+                return false;
+            }
+        } else {
+            return fBM.readPixels(info, pixels, rowBytes, 0, 0);
+        }
     }
 private:
     SkBitmap fBM;
@@ -127,6 +151,54 @@ static SkImageGenerator* make_ras_generator(GrContext*, SkPicture* pic) {
     return new RasterGenerator(bm);
 }
 
+// so we can create a color-table
+static int find_closest(SkPMColor c, const SkPMColor table[], int count) {
+    const int cr = SkGetPackedR32(c);
+    const int cg = SkGetPackedG32(c);
+    const int cb = SkGetPackedB32(c);
+
+    int minDist = 999999999;
+    int index = 0;
+    for (int i = 0; i < count; ++i) {
+        int dr = SkAbs32((int)SkGetPackedR32(table[i]) - cr);
+        int dg = SkAbs32((int)SkGetPackedG32(table[i]) - cg);
+        int db = SkAbs32((int)SkGetPackedB32(table[i]) - cb);
+        int dist = dr + dg + db;
+        if (dist < minDist) {
+            minDist = dist;
+            index = i;
+        }
+    }
+    return index;
+}
+
+static SkImageGenerator* make_ctable_generator(GrContext*, SkPicture* pic) {
+    SkBitmap bm;
+    bm.allocN32Pixels(100, 100);
+    SkCanvas canvas(bm);
+    canvas.clear(0);
+    canvas.translate(-100, -100);
+    canvas.drawPicture(pic);
+
+    const SkPMColor colors[] = {
+        SkPreMultiplyColor(SK_ColorRED),
+        SkPreMultiplyColor(0),
+        SkPreMultiplyColor(SK_ColorBLUE),
+    };
+    const int count = SK_ARRAY_COUNT(colors);
+    SkImageInfo info = SkImageInfo::Make(100, 100, kIndex_8_SkColorType, kPremul_SkAlphaType);
+
+    SkBitmap bm2;
+    SkAutoTUnref<SkColorTable> ct(new SkColorTable(colors, count));
+    bm2.allocPixels(info, nullptr, ct);
+    for (int y = 0; y < info.height(); ++y) {
+        for (int x = 0; x < info.width(); ++x) {
+            *bm2.getAddr8(x, y) = find_closest(*bm.getAddr32(x, y), colors, count);
+        }
+    }
+    return new RasterGenerator(bm2);
+}
+
 class EmptyGenerator : public SkImageGenerator {
 public:
     EmptyGenerator(const SkImageInfo& info) : SkImageGenerator(info) {}
@@ -297,6 +369,7 @@ private:
 };
 DEF_GM( return new ImageCacheratorGM("picture", make_pic_generator); )
 DEF_GM( return new ImageCacheratorGM("raster", make_ras_generator); )
+DEF_GM( return new ImageCacheratorGM("ctable", make_ctable_generator); )
 #if SK_SUPPORT_GPU
     DEF_GM( return new ImageCacheratorGM("texture", make_tex_generator); )
 #endif