Make A8 readbacks work from non-A8 surfaces
authorbsalomon <bsalomon@google.com>
Mon, 25 Jan 2016 22:33:25 +0000 (14:33 -0800)
committerCommit bot <commit-bot@chromium.org>
Mon, 25 Jan 2016 22:33:25 +0000 (14:33 -0800)
Expand testing of A8 readbacks.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1613903005

Review URL: https://codereview.chromium.org/1613903005

src/gpu/gl/GrGLCaps.cpp
src/gpu/gl/GrGLGpu.cpp
tests/ReadWriteAlphaTest.cpp

index 81d0b44..237412a 100644 (file)
@@ -643,7 +643,11 @@ bool GrGLCaps::readPixelsSupported(GrPixelConfig rtConfig,
                                    GrPixelConfig readConfig,
                                    std::function<void (GrGLenum, GrGLint*)> getIntegerv,
                                    std::function<bool ()> bindRenderTarget) const {
-    SkASSERT(this->isConfigRenderable(rtConfig, false));
+    // If it's not possible to even have a render target of rtConfig then read pixels is
+    // not supported regardless of readConfig.
+    if (!this->isConfigRenderable(rtConfig, false)) {
+        return false;
+    }
 
     GrGLenum readFormat;
     GrGLenum readType;
@@ -652,7 +656,22 @@ bool GrGLCaps::readPixelsSupported(GrPixelConfig rtConfig,
     }
 
     if (kGL_GrGLStandard == fStandard) {
-        // All of our renderable configs can be converted to each other by glReadPixels in OpenGL.
+        // Some OpenGL implementations allow GL_ALPHA as a format to glReadPixels. However,
+        // the manual (https://www.opengl.org/sdk/docs/man/) says only these formats are allowed:
+        // GL_STENCIL_INDEX, GL_DEPTH_COMPONENT, GL_DEPTH_STENCIL, GL_RED, GL_GREEN, GL_BLUE,
+        // GL_RGB, GL_BGR, GL_RGBA, and GL_BGRA. We check for the subset that we would use.
+        if (readFormat != GR_GL_RED && readFormat != GR_GL_RGB && readFormat != GR_GL_RGBA &&
+            readFormat != GR_GL_BGRA) {
+            return false;
+        }
+        // There is also a set of allowed types, but all the types we use are in the set:
+        // GL_UNSIGNED_BYTE, GL_BYTE, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT, GL_INT,
+        // GL_HALF_FLOAT, GL_FLOAT, GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV,
+        // GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_5_6_5_REV, GL_UNSIGNED_SHORT_4_4_4_4,
+        // GL_UNSIGNED_SHORT_4_4_4_4_REV, GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV,
+        // GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV,GL_UNSIGNED_INT_10_10_10_2,
+        // GL_UNSIGNED_INT_2_10_10_10_REV, GL_UNSIGNED_INT_24_8, GL_UNSIGNED_INT_10F_11F_11F_REV,
+        // GL_UNSIGNED_INT_5_9_9_9_REV, or GL_FLOAT_32_UNSIGNED_INT_24_8_REV.
         return true;
     }
 
@@ -1070,6 +1089,17 @@ bool GrGLCaps::getExternalFormat(GrPixelConfig surfaceConfig, GrPixelConfig memo
     *externalFormat = fConfigTable[memoryConfig].fFormats.fExternalFormat[usage];
     *externalType = fConfigTable[memoryConfig].fFormats.fExternalType;
 
+    // When GL_RED is supported as a texture format, our alpha-only textures are stored using
+    // GL_RED and we swizzle in order to map all components to 'r'. However, in this case the
+    // surface is not alpha-only and we want alpha to really mean the alpha component of the
+    // texture, not the red component.
+    if (memoryIsAlphaOnly && !surfaceIsAlphaOnly) {
+        if (this->textureRedSupport()) {
+            SkASSERT(GR_GL_RED == *externalFormat);
+            *externalFormat = GR_GL_ALPHA;
+        }
+    }
+
     return true;
 }
 
index bf0b297..94307a6 100644 (file)
@@ -2004,26 +2004,21 @@ bool GrGLGpu::readPixelsSupported(GrSurface* surfaceForConfig, GrPixelConfig rea
     }
 }
 
+static bool requires_srgb_conversion(GrPixelConfig a, GrPixelConfig b) {
+    if (GrPixelConfigIsSRGB(a)) {
+        return !GrPixelConfigIsSRGB(b) && !GrPixelConfigIsAlphaOnly(b);
+    } else if (GrPixelConfigIsSRGB(b)) {
+        return !GrPixelConfigIsSRGB(a) && !GrPixelConfigIsAlphaOnly(a);
+    }
+    return false;
+}
+
 bool GrGLGpu::onGetReadPixelsInfo(GrSurface* srcSurface, int width, int height, size_t rowBytes,
                                   GrPixelConfig readConfig, DrawPreference* drawPreference,
                                   ReadPixelTempDrawInfo* tempDrawInfo) {
-    GrRenderTarget* srcAsRT = srcSurface->asRenderTarget();
-
-    // This subclass can only read pixels from a render target. We could use glTexSubImage2D on
-    // GL versions that support it but we don't today.
-    if (!srcAsRT) {
-        ElevateDrawPreference(drawPreference, kRequireDraw_DrawPreference);
-    }
-
-    if (GrPixelConfigIsSRGB(srcSurface->config()) != GrPixelConfigIsSRGB(readConfig)) {
-        ElevateDrawPreference(drawPreference, kRequireDraw_DrawPreference);
-    }
-
-    tempDrawInfo->fSwizzle = GrSwizzle::RGBA();
-    tempDrawInfo->fReadConfig = readConfig;
+    GrPixelConfig srcConfig = srcSurface->config();
 
-    // These settings we will always want if a temp draw is performed. The config is set below
-    // depending on whether we want to do a R/B swap or not.
+    // These settings we will always want if a temp draw is performed.
     tempDrawInfo->fTempSurfaceDesc.fFlags = kRenderTarget_GrSurfaceFlag;
     tempDrawInfo->fTempSurfaceDesc.fWidth = width;
     tempDrawInfo->fTempSurfaceDesc.fHeight = height;
@@ -2031,10 +2026,33 @@ bool GrGLGpu::onGetReadPixelsInfo(GrSurface* srcSurface, int width, int height,
     tempDrawInfo->fTempSurfaceDesc.fOrigin = kTopLeft_GrSurfaceOrigin; // no CPU y-flip for TL.
     tempDrawInfo->fUseExactScratch = this->glCaps().partialFBOReadIsSlow();
 
-    // Start off assuming that any temp draw should be to the readConfig, then check if that will
-    // be inefficient.
-    GrPixelConfig srcConfig = srcSurface->config();
-    tempDrawInfo->fTempSurfaceDesc.fConfig = readConfig;
+    // For now assume no swizzling, we may change that below.
+    tempDrawInfo->fSwizzle = GrSwizzle::RGBA();
+
+    // Depends on why we need/want a temp draw. Start off assuming no change, the surface we read
+    // from will be srcConfig and we will read readConfig pixels from it.
+    // Not that if we require a draw and return a non-renderable format for the temp surface the
+    // base class will fail for us.
+    tempDrawInfo->fTempSurfaceDesc.fConfig = srcConfig;
+    tempDrawInfo->fReadConfig = readConfig;
+
+    if (requires_srgb_conversion(srcConfig, readConfig)) {
+        if (!this->readPixelsSupported(readConfig, readConfig)) {
+            return false;
+        }
+        // Draw to do srgb to linear conversion or vice versa.
+        ElevateDrawPreference(drawPreference, kRequireDraw_DrawPreference);
+        tempDrawInfo->fTempSurfaceDesc.fConfig = readConfig;
+        tempDrawInfo->fReadConfig = readConfig;
+        return true;
+    }
+
+    GrRenderTarget* srcAsRT = srcSurface->asRenderTarget();
+    if (!srcAsRT) {
+        // For now keep assuming the draw is not a format transformation, just a draw to get to a
+        // RT. We may add additional transformations below.
+        ElevateDrawPreference(drawPreference, kRequireDraw_DrawPreference);
+    }
 
     if (this->glCaps().rgba8888PixelsOpsAreSlow() && kRGBA_8888_GrPixelConfig == readConfig &&
         this->readPixelsSupported(kBGRA_8888_GrPixelConfig, kBGRA_8888_GrPixelConfig)) {
@@ -2056,11 +2074,35 @@ bool GrGLGpu::onGetReadPixelsInfo(GrSurface* srcSurface, int width, int height,
         if (readConfig == kBGRA_8888_GrPixelConfig &&
             this->glCaps().isConfigRenderable(kRGBA_8888_GrPixelConfig, false) &&
             this->readPixelsSupported(kRGBA_8888_GrPixelConfig, kRGBA_8888_GrPixelConfig)) {
-
+            // We're trying to read BGRA but it's not supported. If RGBA is renderable and
+            // we can read it back, then do a swizzling draw to a RGBA and read it back (which
+            // will effectively be BGRA).
             tempDrawInfo->fTempSurfaceDesc.fConfig = kRGBA_8888_GrPixelConfig;
             tempDrawInfo->fSwizzle = GrSwizzle::BGRA();
             tempDrawInfo->fReadConfig = kRGBA_8888_GrPixelConfig;
             ElevateDrawPreference(drawPreference, kRequireDraw_DrawPreference);
+        } else if (readConfig == kAlpha_8_GrPixelConfig) {
+            // onReadPixels implements a fallback for cases where we are want to read kAlpha_8,
+            // it's unsupported, but 32bit RGBA reads are supported.
+            // Don't attempt to do any srgb conversions since we only care about alpha.
+            GrPixelConfig cpuTempConfig = kRGBA_8888_GrPixelConfig;
+            if (GrPixelConfigIsSRGB(srcSurface->config())) {
+                cpuTempConfig = kSRGBA_8888_GrPixelConfig;
+            }
+            if (!this->readPixelsSupported(srcSurface, cpuTempConfig)) {
+                // If we can't read RGBA from the src try to draw to a kRGBA_8888 (or kSRGBA_8888)
+                // first and then onReadPixels will read that to a 32bit temporary buffer.
+                if (this->caps()->isConfigRenderable(cpuTempConfig, false)) {
+                    ElevateDrawPreference(drawPreference, kRequireDraw_DrawPreference);
+                    tempDrawInfo->fTempSurfaceDesc.fConfig = cpuTempConfig;
+                    tempDrawInfo->fReadConfig = kAlpha_8_GrPixelConfig;
+                } else {
+                    return false;
+                }
+            } else {
+                SkASSERT(tempDrawInfo->fTempSurfaceDesc.fConfig == srcConfig);
+                SkASSERT(tempDrawInfo->fReadConfig == kAlpha_8_GrPixelConfig);
+            }
         } else {
             return false;
         }
@@ -2082,46 +2124,71 @@ bool GrGLGpu::onReadPixels(GrSurface* surface,
                            size_t rowBytes) {
     SkASSERT(surface);
 
-    GrGLRenderTarget* tgt = static_cast<GrGLRenderTarget*>(surface->asRenderTarget());
-    if (!tgt) {
+    GrGLRenderTarget* renderTarget = static_cast<GrGLRenderTarget*>(surface->asRenderTarget());
+    if (!renderTarget) {
         return false;
     }
 
     // OpenGL doesn't do sRGB <-> linear conversions when reading and writing pixels.
-    if (GrPixelConfigIsSRGB(surface->config()) != GrPixelConfigIsSRGB(config)) {
+    if (requires_srgb_conversion(surface->config(), config)) {
+        return false;
+    }
+
+    // We have a special case fallback for reading eight bit alpha. We will read back all four 8
+    // bit channels as RGBA and then extract A.
+    if (!this->readPixelsSupported(renderTarget, config)) {
+        // Don't attempt to do any srgb conversions since we only care about alpha.
+        GrPixelConfig tempConfig = kRGBA_8888_GrPixelConfig;
+        if (GrPixelConfigIsSRGB(renderTarget->config())) {
+            tempConfig = kSRGBA_8888_GrPixelConfig;
+        }
+        if (kAlpha_8_GrPixelConfig == config &&
+            this->readPixelsSupported(renderTarget, tempConfig)) {
+            SkAutoTDeleteArray<uint32_t> temp(new uint32_t[width * height * 4]);
+            if (this->onReadPixels(renderTarget, left, top, width, height, tempConfig, temp.get(),
+                                   width*4)) {
+                uint8_t* dst = reinterpret_cast<uint8_t*>(buffer);
+                for (int j = 0; j < height; ++j) {
+                    for (int i = 0; i < width; ++i) {
+                        dst[j*rowBytes + i] = (0xFF000000U & temp[j*width+i]) >> 24;
+                    }
+                }
+                return true;
+            }
+        }
         return false;
     }
 
     GrGLenum externalFormat;
     GrGLenum externalType;
-    if (!this->glCaps().getReadPixelsFormat(surface->config(), config, &externalFormat,
+    if (!this->glCaps().getReadPixelsFormat(renderTarget->config(), config, &externalFormat,
                                             &externalType)) {
         return false;
     }
     bool flipY = kBottomLeft_GrSurfaceOrigin == surface->origin();
 
     // resolve the render target if necessary
-    switch (tgt->getResolveType()) {
+    switch (renderTarget->getResolveType()) {
         case GrGLRenderTarget::kCantResolve_ResolveType:
             return false;
         case GrGLRenderTarget::kAutoResolves_ResolveType:
-            this->flushRenderTarget(tgt, &SkIRect::EmptyIRect());
+            this->flushRenderTarget(renderTarget, &SkIRect::EmptyIRect());
             break;
         case GrGLRenderTarget::kCanResolve_ResolveType:
-            this->onResolveRenderTarget(tgt);
+            this->onResolveRenderTarget(renderTarget);
             // we don't track the state of the READ FBO ID.
             fStats.incRenderTargetBinds();
-            GL_CALL(BindFramebuffer(GR_GL_READ_FRAMEBUFFER, tgt->textureFBOID()));
+            GL_CALL(BindFramebuffer(GR_GL_READ_FRAMEBUFFER, renderTarget->textureFBOID()));
             break;
         default:
             SkFAIL("Unknown resolve type");
     }
 
-    const GrGLIRect& glvp = tgt->getViewport();
+    const GrGLIRect& glvp = renderTarget->getViewport();
 
     // the read rect is viewport-relative
     GrGLIRect readRect;
-    readRect.setRelativeTo(glvp, left, top, width, height, tgt->origin());
+    readRect.setRelativeTo(glvp, left, top, width, height, renderTarget->origin());
 
     size_t tightRowBytes = GrBytesPerPixel(config) * width;
 
index 1ee6b09..0a84417 100644 (file)
@@ -8,7 +8,7 @@
 #include "Test.h"
 
 // This test is specific to the GPU backend.
-#if SK_SUPPORT_GPU && !defined(SK_BUILD_FOR_ANDROID)
+#if SK_SUPPORT_GPU
 
 #include "GrContext.h"
 #include "SkGpuDevice.h"
@@ -18,88 +18,153 @@ static const int X_SIZE = 13;
 static const int Y_SIZE = 13;
 
 DEF_GPUTEST_FOR_RENDERING_CONTEXTS(ReadWriteAlpha, reporter, context) {
-    unsigned char textureData[X_SIZE][Y_SIZE];
+    unsigned char alphaData[X_SIZE][Y_SIZE];
 
-    memset(textureData, 0, X_SIZE * Y_SIZE);
+    memset(alphaData, 0, X_SIZE * Y_SIZE);
 
-    GrSurfaceDesc desc;
-
-    // let Skia know we will be using this texture as a render target
-    desc.fFlags     = kRenderTarget_GrSurfaceFlag;
-    // it is a single channel texture
-    desc.fConfig    = kAlpha_8_GrPixelConfig;
-    desc.fWidth     = X_SIZE;
-    desc.fHeight    = Y_SIZE;
-
-    // We are initializing the texture with zeros here
-    GrTexture* texture = context->textureProvider()->createTexture(desc, false, textureData, 0);
-    if (!texture) {
-        return;
-    }
-
-    SkAutoTUnref<GrTexture> au(texture);
+    bool match;
+    unsigned char readback[X_SIZE][Y_SIZE];
 
-    // create a distinctive texture
-    for (int y = 0; y < Y_SIZE; ++y) {
-        for (int x = 0; x < X_SIZE; ++x) {
-            textureData[x][y] = x*Y_SIZE+y;
+    for (int rt = 0; rt < 2; ++rt) {
+        GrSurfaceDesc desc;
+        // let Skia know we will be using this texture as a render target
+        desc.fFlags     = rt ? kRenderTarget_GrSurfaceFlag : kNone_GrSurfaceFlags;
+        // it is a single channel texture
+        desc.fConfig    = kAlpha_8_GrPixelConfig;
+        desc.fWidth     = X_SIZE;
+        desc.fHeight    = Y_SIZE;
+
+        // We are initializing the texture with zeros here
+        SkAutoTUnref<GrTexture> texture(
+            context->textureProvider()->createTexture(desc, false, alphaData, 0));
+        if (!texture) {
+            if (!rt) {
+                ERRORF(reporter, "Could not create alpha texture.");
+            }
+            continue;
         }
-    }
 
-    // upload the texture
-    texture->writePixels(0, 0, desc.fWidth, desc.fHeight, desc.fConfig,
-                         textureData, 0);
+        // create a distinctive texture
+        for (int y = 0; y < Y_SIZE; ++y) {
+            for (int x = 0; x < X_SIZE; ++x) {
+                alphaData[x][y] = y*X_SIZE+x;
+            }
+        }
 
-    unsigned char readback[X_SIZE][Y_SIZE];
+        // upload the texture
+        texture->writePixels(0, 0, desc.fWidth, desc.fHeight, desc.fConfig,
+                             alphaData, 0);
 
-    // clear readback to something non-zero so we can detect readback failures
-    memset(readback, 0x1, X_SIZE * Y_SIZE);
+        // clear readback to something non-zero so we can detect readback failures
+        memset(readback, 0x1, X_SIZE * Y_SIZE);
 
-    // read the texture back
-    texture->readPixels(0, 0, desc.fWidth, desc.fHeight, desc.fConfig,
-                        readback, 0);
+        // read the texture back
+        texture->readPixels(0, 0, desc.fWidth, desc.fHeight, desc.fConfig,
+                            readback, 0);
 
-    // make sure the original & read back versions match
-    bool match = true;
+        // make sure the original & read back versions match
+        match = true;
 
-    for (int y = 0; y < Y_SIZE; ++y) {
-        for (int x = 0; x < X_SIZE; ++x) {
-            if (textureData[x][y] != readback[x][y]) {
-                match = false;
+        for (int y = 0; y < Y_SIZE && match; ++y) {
+            for (int x = 0; x < X_SIZE && match; ++x) {
+                if (alphaData[x][y] != readback[x][y]) {
+                    SkDebugf("Failed alpha readback. Expected: 0x%02x, "
+                             "Got: 0x%02x at (%d,%d), rt: %d", alphaData[x][y], readback[x][y], x,
+                             y, rt);
+                    match = false;
+                }
             }
         }
-    }
-
-    REPORTER_ASSERT(reporter, match);
 
-    // Now try writing on the single channel texture
-    SkSurfaceProps props(SkSurfaceProps::kLegacyFontHost_InitType);
-    SkAutoTUnref<SkBaseDevice> device(SkGpuDevice::Create(texture->asRenderTarget(), &props,
-                                                          SkGpuDevice::kUninit_InitContents));
-    SkCanvas canvas(device);
+        // Now try writing on the single channel texture (if we could create as a RT).
+        if (texture->asRenderTarget()) {
+            SkSurfaceProps props(SkSurfaceProps::kLegacyFontHost_InitType);
+            SkAutoTUnref<SkBaseDevice> device(SkGpuDevice::Create(
+                texture->asRenderTarget(), &props, SkGpuDevice::kUninit_InitContents));
+            SkCanvas canvas(device);
 
-    SkPaint paint;
+            SkPaint paint;
 
-    const SkRect rect = SkRect::MakeLTRB(-10, -10, X_SIZE + 10, Y_SIZE + 10);
+            const SkRect rect = SkRect::MakeLTRB(-10, -10, X_SIZE + 10, Y_SIZE + 10);
 
-    paint.setColor(SK_ColorWHITE);
+            paint.setColor(SK_ColorWHITE);
 
-    canvas.drawRect(rect, paint);
+            canvas.drawRect(rect, paint);
 
-    texture->readPixels(0, 0, desc.fWidth, desc.fHeight, desc.fConfig,
-                        readback, 0);
+            texture->readPixels(0, 0, desc.fWidth, desc.fHeight, desc.fConfig, readback, 0);
 
-    match = true;
+            match = true;
 
-    for (int y = 0; y < Y_SIZE; ++y) {
-        for (int x = 0; x < X_SIZE; ++x) {
-            if (0xFF != readback[x][y]) {
-                match = false;
+            for (int y = 0; y < Y_SIZE && match; ++y) {
+                for (int x = 0; x < X_SIZE && match; ++x) {
+                    if (0xFF != readback[x][y]) {
+                        ERRORF(reporter,
+                               "Failed alpha readback after clear. Expected: 0xFF, Got: 0x%02x at "
+                               "(%d,%d)", readback[x][y], x, y);
+                        match = false;
+                    }
+                }
             }
         }
     }
 
-    REPORTER_ASSERT(reporter, match);
+    static const GrPixelConfig kRGBAConfigs[] {
+        kRGBA_8888_GrPixelConfig,
+        kBGRA_8888_GrPixelConfig,
+        kSRGBA_8888_GrPixelConfig
+    };
+
+    // Attempt to read back just alpha from a RGBA/BGRA texture. Once with a texture-only src and
+    // once with a render target.
+    for (auto cfg : kRGBAConfigs) {
+        for (int rt = 0; rt < 2; ++rt) {
+            GrSurfaceDesc desc;
+            desc.fFlags     = rt ? kRenderTarget_GrSurfaceFlag : kNone_GrSurfaceFlags;
+            desc.fConfig    = cfg;
+            desc.fWidth     = X_SIZE;
+            desc.fHeight    = Y_SIZE;
+
+            uint32_t rgbaData[X_SIZE][Y_SIZE];
+            // Make the alpha channel of the rgba texture come from alphaData.
+            for (int y = 0; y < Y_SIZE; ++y) {
+                for (int x = 0; x < X_SIZE; ++x) {
+                    rgbaData[x][y] = GrColorPackRGBA(6, 7, 8, alphaData[x][y]);
+                }
+            }
+            SkAutoTUnref<GrTexture> texture(
+                context->textureProvider()->createTexture(desc, false, rgbaData, 0));
+            if (!texture) {
+                // We always expect to be able to create a RGBA texture
+                if (!rt  && kRGBA_8888_GrPixelConfig == desc.fConfig) {
+                    ERRORF(reporter, "Failed to create RGBA texture.");
+                }
+                continue;
+            }
+
+            // clear readback to something non-zero so we can detect readback failures
+            memset(readback, 0x0, X_SIZE * Y_SIZE);
+
+            // read the texture back
+            texture->readPixels(0, 0, desc.fWidth, desc.fHeight, kAlpha_8_GrPixelConfig, readback,
+                                0);
+
+            match = true;
+
+            for (int y = 0; y < Y_SIZE && match; ++y) {
+                for (int x = 0; x < X_SIZE && match; ++x) {
+                    if (alphaData[x][y] != readback[x][y]) {
+                        texture->readPixels(0, 0, desc.fWidth, desc.fHeight,
+                                            kAlpha_8_GrPixelConfig, readback, 0);
+                        ERRORF(reporter,
+                               "Failed alpha readback from cfg %d. Expected: 0x%02x, Got: 0x%02x at"
+                               " (%d,%d), rt:%d", desc.fConfig, alphaData[x][y], readback[x][y], x,
+                               y, rt);
+                        match = false;
+                    }
+                }
+            }
+        }
+    }
 }
 
 #endif