start experimenting with 64bit frame-buffers

gm/xferu64.cpp

Index: gm/xferu64.cpp
diff --git a/gm/xferu64.cpp b/gm/xferu64.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..03fc8864b56876eac812082e246f54e3bb6c0bb4
--- /dev/null
+++ b/gm/xferu64.cpp
@@ -0,0 +1,149 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+#include "SkCanvas.h"
+#include "SkImageInfo.h"
+#include "SkXfermode.h"
+#include "SkHalf.h"
+#include "SkImage.h"
+
+static SkPMColor f16_to_pmcolor(uint64_t src) {
+    SkPMColor dst;
+    const SkHalf* sptr = reinterpret_cast<const SkHalf*>(&src);
+    uint8_t* dptr = reinterpret_cast<uint8_t*>(&dst);
+    for (int i = 0; i < 4; ++i) {
+        float f = SkHalfToFloat(sptr[i]);
+        dptr[i] = SkToU8((int)(f * 255 + 0.5f));
+    }
+    return dst;
+}
+
+static SkPMColor u16_to_pmcolor(uint64_t src) {
+    SkPMColor dst;
+    const uint16_t* sptr = reinterpret_cast<const uint16_t*>(&src);
+    uint8_t* dptr = reinterpret_cast<uint8_t*>(&dst);
+    for (int i = 0; i < 4; ++i) {
+        dptr[i] = sptr[i] >> 8;
+    }
+    return dst;
+}
+
+static SkImage* new_u64_image(const SkBitmap& src, uint32_t flags) {
+    SkBitmap dst;
+    dst.allocN32Pixels(src.width(), src.height());
+    SkPixmap srcPM, dstPM;
+    src.peekPixels(&srcPM);
+    dst.peekPixels(&dstPM);
+
+    for (int y = 0; y < srcPM.height(); ++y) {
+        for (int x = 0; x < srcPM.width(); ++x) {
+            uint64_t srcP = *srcPM.addr64(x, y);
+            uint32_t* dstP = dstPM.writable_addr32(x, y);
+
+            if (flags & SkXfermode::kDstIsFloat16_U64Flag) {
+                *dstP = f16_to_pmcolor(srcP);
+            } else {
+                *dstP = u16_to_pmcolor(srcP);
+            }
+        }
+    }
+    return SkImage::NewRasterCopy(dstPM.info(), dstPM.addr(), dstPM.rowBytes());
+}
+
+static void draw_rect(SkCanvas* canvas, const SkRect& r, SkColor c, uint32_t u64_flags,
+                      const SkAlpha aa[]) {
+    const SkIRect ir = r.round();
+    const SkImageInfo info = SkImageInfo::Make(ir.width(), ir.height(),
+                                               kRGBA_F16_SkColorType, kPremul_SkAlphaType);
+
+    SkBitmap bm;
+    bm.allocPixels(info);
+    SkPixmap pm;
+    bm.peekPixels(&pm);
+    memset(pm.writable_addr(), 0, pm.getSafeSize());
+
+    if (SkColorGetA(c) == 0xFF) {
+        u64_flags |= SkXfermode::kSrcIsOpaque_PM4fFlag;
+    }
+
+    const SkXfermode::U64State state { nullptr, u64_flags };
+
+    const SkPM4f src = SkColor4f::FromColor(c).premul();
+    auto proc1 = SkXfermode::GetU64Proc1(SkXfermode::kSrcOver_Mode, u64_flags);
+    for (int y = 0; y < ir.height()/2; ++y) {
+        proc1(state, pm.writable_addr64(0, y), src, ir.width(), aa);
+    }
+    
+    SkPM4f buffer[1000];
+    for (int i = 0; i < ir.width(); ++i) {
+        buffer[i] = src;
+    }
+    auto procN = SkXfermode::GetU64ProcN(SkXfermode::kSrcOver_Mode, u64_flags);
+    for (int y = ir.height()/2 + 1; y < ir.height(); ++y) {
+        procN(state, pm.writable_addr64(0, y), buffer, ir.width(), aa);
+    }
+
+    SkAutoTUnref<SkImage> image(new_u64_image(bm, u64_flags));
+    canvas->drawImage(image, r.left(), r.top(), nullptr);
+}
+
+/*
+ *  Test SkXfer4fProcs directly for src-over, comparing them to current SkColor blits.
+ */
+DEF_SIMPLE_GM(xfer_u64_srcover, canvas, 580, 760) {
+    const int IW = 50;
+    const SkScalar W = IW;
+    const SkScalar H = 100;
+
+    const int32_t flags[] = {
+        -1,                                 // normal
+        0,                                  // U16 components
+        SkXfermode::kDstIsFloat16_U64Flag,  // F16 components
+    };
+    const SkColor colors[] = {
+        SK_ColorBLACK, SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE,
+        0x88000000, 0x88FF0000, 0x8800FF00, 0x880000FF
+    };
+    
+    uint8_t aa_scanline[IW];
+    for (int i = 0; i < IW; ++i) {
+        aa_scanline[i] = i * 255 / (IW - 1);
+    }
+    uint8_t const* aa_table[] = { nullptr, aa_scanline };
+
+    SkBitmap mask;
+    mask.installPixels(SkImageInfo::MakeA8(IW, 1), aa_scanline, IW);
+
+    canvas->translate(20, 20);
+
+    const SkRect r = SkRect::MakeWH(W, H);
+    for (const uint8_t* aa : aa_table) {
+        canvas->save();
+        for (auto flag : flags) {
+            canvas->save();
+            for (SkColor c : colors) {
+                if (flag < 0) {
+                    SkPaint p;
+                    p.setColor(c);
+                    if (aa) {
+                        canvas->drawBitmapRect(mask, r, &p);
+                    } else {
+                        canvas->drawRect(r, p);
+                    }
+                } else {
+                    draw_rect(canvas, r, c, flag, aa);
+                }
+                canvas->translate(W + 20, 0);
+            }
+            canvas->restore();
+            canvas->translate(0, H + 20);
+        }
+        canvas->restore();
+        canvas->translate(0, (H + 20) * SK_ARRAY_COUNT(flags) + 20);
+    }
+}