Add ability to extract YUV planes from SkImage

src/gpu/GrTextureToYUVPlanes.cpp

+/*
+ * 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 "GrTextureToYUVPlanes.h"
+#include "effects/GrSimpleTextureEffect.h"
+#include "effects/GrYUVEffect.h"
+#include "GrClip.h"
+#include "GrContext.h"
+#include "GrDrawContext.h"
+#include "GrPaint.h"
+#include "GrTextureProvider.h"
+
+namespace {
+    using CreateFPProc = const GrFragmentProcessor* (*)(const GrFragmentProcessor*,
+                                                        SkYUVColorSpace colorSpace);
+};
+
+static bool convert_texture(GrTexture* src, GrDrawContext* dst, int dstW, int dstH,
+                            SkYUVColorSpace colorSpace, CreateFPProc proc) {
+
+    SkScalar xScale = SkIntToScalar(src->width()) / dstW / src->width();
+    SkScalar yScale = SkIntToScalar(src->height()) / dstH / src->height();
+    GrTextureParams::FilterMode filter;
+    if (dstW == src->width() && dstW == src->height()) {
+        filter = GrTextureParams::kNone_FilterMode;
+    } else {
+        filter = GrTextureParams::kBilerp_FilterMode;
+    }
+
+    SkAutoTUnref<const GrFragmentProcessor> fp(
+            GrSimpleTextureEffect::Create(src, SkMatrix::MakeScale(xScale, yScale), filter));
+    if (!fp) {
+        return false;
+    }
+    fp.reset(proc(fp, colorSpace));
+    if (!fp) {
+        return false;
+    }
+    GrPaint paint;
+    paint.setPorterDuffXPFactory(SkXfermode::kSrc_Mode);
+    paint.addColorFragmentProcessor(fp);
+    dst->drawRect(GrClip::WideOpen(), paint, SkMatrix::I(), SkRect::MakeIWH(dstW, dstH));
+    return true;
+}
+
+bool GrTextureToYUVPlanes(GrTexture* texture, const SkISize sizes[3], void* const planes[3],
+                          const size_t rowBytes[3], SkYUVColorSpace colorSpace) {
+    if (GrContext* context = texture->getContext()) {
+        // Depending on the relative sizes of the y, u, and v planes we may do 1 to 3 draws/
+        // readbacks.
+        SkAutoTUnref<GrTexture> yuvTex;
+        SkAutoTUnref<GrTexture> yTex;
+        SkAutoTUnref<GrTexture> uvTex;
+        SkAutoTUnref<GrTexture> uTex;
+        SkAutoTUnref<GrTexture> vTex;
+
+        GrPixelConfig singleChannelPixelConfig;
+        if (context->caps()->isConfigRenderable(kAlpha_8_GrPixelConfig, false)) {
+            singleChannelPixelConfig = kAlpha_8_GrPixelConfig;
+        } else {
+            singleChannelPixelConfig = kRGBA_8888_GrPixelConfig;
+        }
+
+        if (sizes[0] == sizes[1] && sizes[1] == sizes[2]) {

[robertphillips, 2016/01/29 20:33:13]

// YUV444 - only 1 draw/readback

?

[bsalomon, 2016/02/01 20:27:45]

I put a comment above the first if about the three cases.

+            GrSurfaceDesc yuvDesc;
+            yuvDesc.fConfig = kRGBA_8888_GrPixelConfig;
+            yuvDesc.fFlags = kRenderTarget_GrSurfaceFlag;
+            yuvDesc.fWidth = sizes[0].fWidth;
+            yuvDesc.fHeight = sizes[0].fHeight;
+            yuvTex.reset(context->textureProvider()->createApproxTexture(yuvDesc));
+            if (!yuvTex) {
+                return false;
+            }
+        } else {
+            GrSurfaceDesc yDesc;
+            yDesc.fConfig = singleChannelPixelConfig;
+            yDesc.fFlags = kRenderTarget_GrSurfaceFlag;
+            yDesc.fWidth = sizes[0].fWidth;
+            yDesc.fHeight = sizes[0].fHeight;
+            yTex.reset(context->textureProvider()->createApproxTexture(yDesc));
+            if (!yTex) {
+                return false;
+            }
+            if (sizes[1] == sizes[2]) {

[robertphillips, 2016/01/29 20:33:13]

// Something like 422 or 411 - only 2 draws/readbacks (y & uv)

?

+                GrSurfaceDesc uvDesc;
+                // TODO: Add support for GL_RG when available.
+                uvDesc.fConfig = kRGBA_8888_GrPixelConfig;
+                uvDesc.fFlags = kRenderTarget_GrSurfaceFlag;
+                uvDesc.fWidth = sizes[1].fWidth;
+                uvDesc.fHeight = sizes[1].fHeight;
+                uvTex.reset(context->textureProvider()->createApproxTexture(uvDesc));
+                if (!uvTex) {
+                    return false;
+                }
+            } else {

[robertphillips, 2016/01/29 20:33:13]

// Each channel is different sized - 3 draws/readbacks 

?

+                GrSurfaceDesc uvDesc;
+                uvDesc.fConfig = singleChannelPixelConfig;
+                uvDesc.fFlags = kRenderTarget_GrSurfaceFlag;
+                uvDesc.fWidth = sizes[1].fWidth;
+                uvDesc.fHeight = sizes[1].fHeight;
+                uTex.reset(context->textureProvider()->createApproxTexture(uvDesc));
+                uvDesc.fWidth = sizes[2].fWidth;
+                uvDesc.fHeight = sizes[2].fHeight;
+                vTex.reset(context->textureProvider()->createApproxTexture(uvDesc));
+                if (!uTex || !vTex) {
+                    return false;
+                }
+            }
+        }
+
+        // Do all the draws before any readback.
+        if (yuvTex) {
+            SkAutoTUnref<GrDrawContext> dc(context->drawContext(yuvTex->asRenderTarget()));
+            if (!dc) {
+                return false;
+            }
+            if (!convert_texture(texture, dc, sizes[0].fWidth, sizes[0].fHeight, colorSpace,
+                                 GrYUVEffect::CreateRGBToYUV)) {
+                return false;
+            }
+
+        } else {
+            SkASSERT(yTex);
+            SkAutoTUnref<GrDrawContext> dc(context->drawContext(yTex->asRenderTarget()));
+            if (!dc) {
+                return false;
+            }
+            if (!convert_texture(texture, dc, sizes[0].fWidth, sizes[0].fHeight, colorSpace,
+                                 GrYUVEffect::CreateRGBToY)) {
+                return false;
+            }
+            if (uvTex) {
+                dc.reset(context->drawContext(uvTex->asRenderTarget()));
+                if (!dc) {
+                    return false;
+                }
+                if (!convert_texture(texture, dc, sizes[1].fWidth, sizes[1].fHeight,
+                                     colorSpace,  GrYUVEffect::CreateRGBToUV)) {
+                    return false;
+                }
+            } else {
+                SkASSERT(uTex && vTex);
+                dc.reset(context->drawContext(uTex->asRenderTarget()));
+                if (!dc) {
+                    return false;
+                }
+                if (!convert_texture(texture, dc, sizes[1].fWidth, sizes[1].fHeight,
+                                     colorSpace, GrYUVEffect::CreateRGBToU)) {
+                    return false;
+                }
+                dc.reset(context->drawContext(vTex->asRenderTarget()));
+                if (!dc) {
+                    return false;
+                }
+                if (!convert_texture(texture, dc, sizes[2].fWidth, sizes[2].fHeight,
+                                     colorSpace, GrYUVEffect::CreateRGBToV)) {
+                    return false;
+                }
+            }
+        }
+
+        if (yuvTex) {

[robertphillips, 2016/01/29 20:33:13]

The use of sizes[0], [1] & [2] mildly bothers me here. Can we just assert
they're all the same and just use one ?

[bsalomon, 2016/02/01 20:27:45]

Compromise - assert and then use another scoped var: yuvSize.

+            // We have no kRGB_888 pixel format, so readback rgba and then copy three channels.
+            SkAutoSTMalloc<128 * 128, uint32_t> tempYUV(sizes[0].fWidth * sizes[0].fHeight);
+            if (!yuvTex->readPixels(0, 0, sizes[0].fWidth, sizes[0].fHeight,
+                                    kRGBA_8888_GrPixelConfig, tempYUV.get(), 0)) {
+                return false;
+            }
+            size_t yRowBytes = rowBytes[0] ? rowBytes[0] : sizes[0].fWidth;
+            size_t uRowBytes = rowBytes[1] ? rowBytes[1] : sizes[1].fWidth;
+            size_t vRowBytes = rowBytes[2] ? rowBytes[2] : sizes[2].fWidth;
+            for (int j = 0; j < sizes[1].fHeight; ++j) {
+                for (int i = 0; i < sizes[1].fWidth; ++i) {
+                    // These writes could surely be made more efficient.
+                    uint32_t y = GrColorUnpackR(tempYUV.get()[j * sizes[1].fWidth + i]);
+                    uint32_t u = GrColorUnpackG(tempYUV.get()[j * sizes[1].fWidth + i]);
+                    uint32_t v = GrColorUnpackB(tempYUV.get()[j * sizes[1].fWidth + i]);
+                    uint8_t* yLoc = ((uint8_t*)planes[0]) + j * yRowBytes + i;
+                    uint8_t* uLoc = ((uint8_t*)planes[1]) + j * uRowBytes + i;
+                    uint8_t* vLoc = ((uint8_t*)planes[2]) + j * vRowBytes + i;
+                    *yLoc = y;
+                    *uLoc = u;
+                    *vLoc = v;
+                }
+            }
+            return true;
+        } else {
+            SkASSERT(yTex);
+            if (!yTex->readPixels(0, 0, sizes[0].fWidth, sizes[0].fHeight,
+                                  kAlpha_8_GrPixelConfig, planes[0], rowBytes[0])) {
+                return false;
+            }
+            if (uvTex) {
+                // We have no kRG_88 pixel format, so readback rgba and then copy two channels.
+                SkAutoSTMalloc<128 * 128, uint32_t> tempUV(sizes[1].fWidth * sizes[1].fHeight);
+                if (!uvTex->readPixels(0, 0, sizes[1].fWidth, sizes[1].fHeight,
+                                       kRGBA_8888_GrPixelConfig, tempUV.get(), 0)) {
+                    return false;
+                }

[robertphillips, 2016/01/29 20:33:13]

SkASSERT(sizes[1].fWidth == sizes[2].fWidth); ?

[bsalomon, 2016/02/01 20:27:45]

Done.

+                size_t uRowBytes = rowBytes[1] ? rowBytes[1] : sizes[1].fWidth;
+                size_t vRowBytes = rowBytes[2] ? rowBytes[2] : sizes[2].fWidth;
+                for (int j = 0; j < sizes[1].fHeight; ++j) {
+                    for (int i = 0; i < sizes[1].fWidth; ++i) {
+                        // These writes could surely be made more efficient.
+                        uint32_t u = GrColorUnpackR(tempUV.get()[j * sizes[1].fWidth + i]);
+                        uint32_t v = GrColorUnpackG(tempUV.get()[j * sizes[1].fWidth + i]);
+                        uint8_t* uLoc = ((uint8_t*)planes[1]) + j * uRowBytes + i;
+                        uint8_t* vLoc = ((uint8_t*)planes[2]) + j * vRowBytes + i;
+                        *uLoc = u;
+                        *vLoc = v;
+                    }
+                }
+                return true;
+            } else {
+                SkASSERT(uTex && vTex);
+                if (!uTex->readPixels(0, 0, sizes[1].fWidth, sizes[1].fHeight,
+                                      kAlpha_8_GrPixelConfig, planes[1], rowBytes[1])) {
+                    return false;
+                }
+                if (!vTex->readPixels(0, 0, sizes[2].fWidth, sizes[2].fHeight,
+                                      kAlpha_8_GrPixelConfig, planes[2], rowBytes[2])) {
+                    return false;
+                }
+                return true;
+            }
+        }
+    }
+    return false;
+}