Add a zoom filter to Skia. This will be used on ChromeOS to implement the screen magnifier.

Committed on behalf of zork@chromium.org

Review URL: http://codereview.appspot.com/6354065/


git-svn-id: http://skia.googlecode.com/svn/trunk@5056 2bbb7eff-a529-9590-31e7-b0007b416f81

4 files changed, 335 insertions, 1 deletions

diff --git a/src/effects/SkMagnifierImageFilter.cpp b/src/effects/SkMagnifierImageFilter.cpp
new file mode 100644
index 0000000000..dbd9135891
--- /dev/null
+++ b/src/effects/SkMagnifierImageFilter.cpp
@@ -0,0 +1,331 @@
+/*
+ * Copyright 2012 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkBitmap.h"
+#include "SkMagnifierImageFilter.h"
+#include "SkColorPriv.h"
+#include "SkFlattenableBuffers.h"
+#include "gl/GrGLTexture.h"
+
+#include <algorithm>
+
+////////////////////////////////////////////////////////////////////////////////
+#include "effects/GrSingleTextureEffect.h"
+#include "gl/GrGLProgramStage.h"
+#include "gl/GrGLSL.h"
+#include "gl/GrGLTexture.h"
+#include "GrProgramStageFactory.h"
+
+class GrGLMagnifierEffect;
+
+class GrMagnifierEffect : public GrSingleTextureEffect {
+
+public:
+    GrMagnifierEffect(GrTexture* texture,
+                      float xOffset,
+                      float yOffset,
+                      float xZoom,
+                      float yZoom,
+                      float xInset,
+                      float yInset)
+        : GrSingleTextureEffect(texture)
+        , fXOffset(xOffset)
+        , fYOffset(yOffset)
+        , fXZoom(xZoom)
+        , fYZoom(yZoom)
+        , fXInset(xInset)
+        , fYInset(yInset) {}
+
+    virtual ~GrMagnifierEffect() {};
+
+    static const char* Name() { return "Magnifier"; }
+
+    virtual const GrProgramStageFactory& getFactory() const SK_OVERRIDE;
+    virtual bool isEqual(const GrCustomStage&) const SK_OVERRIDE;
+
+    float x_offset() const { return fXOffset; }
+    float y_offset() const { return fYOffset; }
+    float x_zoom() const { return fXZoom; }
+    float y_zoom() const { return fYZoom; }
+    float x_inset() const { return fXInset; }
+    float y_inset() const { return fYInset; }
+
+    typedef GrGLMagnifierEffect GLProgramStage;
+
+private:
+    GR_DECLARE_CUSTOM_STAGE_TEST;
+
+    float fXOffset;
+    float fYOffset;
+    float fXZoom;
+    float fYZoom;
+    float fXInset;
+    float fYInset;
+
+    typedef GrSingleTextureEffect INHERITED;
+};
+
+// For brevity
+typedef GrGLUniformManager::UniformHandle UniformHandle;
+
+class GrGLMagnifierEffect : public GrGLProgramStage {
+public:
+    GrGLMagnifierEffect(const GrProgramStageFactory& factory,
+                        const GrCustomStage& stage);
+
+    virtual void setupVariables(GrGLShaderBuilder* state) SK_OVERRIDE;
+    virtual void emitVS(GrGLShaderBuilder* state,
+                        const char* vertexCoords) SK_OVERRIDE;
+    virtual void emitFS(GrGLShaderBuilder* state,
+                        const char* outputColor,
+                        const char* inputColor,
+                        const char* samplerName) SK_OVERRIDE;
+
+    virtual void setData(const GrGLUniformManager& uman,
+                         const GrCustomStage& data,
+                         const GrRenderTarget*,
+                         int stageNum) SK_OVERRIDE;
+
+    static inline StageKey GenKey(const GrCustomStage&, const GrGLCaps&);
+
+private:
+
+    UniformHandle  fOffsetVar;
+    UniformHandle  fZoomVar;
+    UniformHandle  fInsetVar;
+
+    typedef GrGLProgramStage INHERITED;
+};
+
+GrGLMagnifierEffect::GrGLMagnifierEffect(const GrProgramStageFactory& factory,
+                                         const GrCustomStage& stage)
+    : GrGLProgramStage(factory)
+    , fOffsetVar(GrGLUniformManager::kInvalidUniformHandle)
+    , fZoomVar(GrGLUniformManager::kInvalidUniformHandle)
+    , fInsetVar(GrGLUniformManager::kInvalidUniformHandle) {
+}
+
+void GrGLMagnifierEffect::setupVariables(GrGLShaderBuilder* state) {
+    fOffsetVar = state->addUniform(
+        GrGLShaderBuilder::kFragment_ShaderType |
+        GrGLShaderBuilder::kVertex_ShaderType,
+        kVec2f_GrSLType, "uOffset");
+    fZoomVar = state->addUniform(
+        GrGLShaderBuilder::kFragment_ShaderType |
+        GrGLShaderBuilder::kVertex_ShaderType,
+        kVec2f_GrSLType, "uZoom");
+    fInsetVar = state->addUniform(
+        GrGLShaderBuilder::kFragment_ShaderType |
+        GrGLShaderBuilder::kVertex_ShaderType,
+        kVec2f_GrSLType, "uInset");
+}
+
+void GrGLMagnifierEffect::emitVS(GrGLShaderBuilder* state,
+                                 const char* vertexCoords) {
+}
+
+void GrGLMagnifierEffect::emitFS(GrGLShaderBuilder* state,
+                                 const char* outputColor,
+                                 const char* inputColor,
+                                 const char* samplerName) {
+    SkString* code = &state->fFSCode;
+
+    code->appendf("\t\tvec2 coord = %s;\n", state->fSampleCoords.c_str());
+    code->appendf("\t\tvec2 zoom_coord = %s + %s / %s;\n",
+                  state->getUniformCStr(fOffsetVar),
+                  state->fSampleCoords.c_str(),
+                  state->getUniformCStr(fZoomVar));
+
+    code->appendf("\t\tvec2 delta = min(coord, vec2(1.0, 1.0) - coord);\n");
+
+    code->appendf(
+        "\t\tdelta = delta / %s;\n", state->getUniformCStr(fInsetVar));
+
+    code->appendf("\t\tfloat weight = 0.0;\n");
+    code->appendf("\t\tif (delta.s < 2.0 && delta.t < 2.0) {\n");
+    code->appendf("\t\t\tdelta = vec2(2.0, 2.0) - delta;\n");
+    code->appendf("\t\t\tfloat dist = length(delta);\n");
+    code->appendf("\t\t\tdist = max(2.0 - dist, 0.0);\n");
+    code->appendf("\t\t\tweight = min(dist * dist, 1.0);\n");
+    code->appendf("\t\t} else {\n");
+    code->appendf("\t\t\tvec2 delta_squared = delta * delta;\n");
+    code->appendf(
+        "\t\t\tweight = min(min(delta_squared.s, delta_squared.y), 1.0);\n");
+    code->appendf("\t\t}\n");
+
+    code->appendf("\t\tvec2 mix_coord = mix(coord, zoom_coord, weight);\n");
+    code->appendf("\t\tvec4 output_color = ");
+    state->emitTextureLookup(samplerName, "mix_coord");
+    code->appendf(";\n");
+
+    code->appendf("\t\t%s = output_color;", outputColor);
+}
+
+void GrGLMagnifierEffect::setData(const GrGLUniformManager& uman,
+                                  const GrCustomStage& data,
+                                  const GrRenderTarget*,
+                                  int stageNum) {
+    const GrMagnifierEffect& zoom =
+        static_cast<const GrMagnifierEffect&>(data);
+
+    uman.set2f(fOffsetVar, zoom.x_offset(), zoom.y_offset());
+    uman.set2f(fZoomVar, zoom.x_zoom(), zoom.y_zoom());
+    uman.set2f(fInsetVar, zoom.x_inset(), zoom.y_inset());
+}
+
+GrGLProgramStage::StageKey GrGLMagnifierEffect::GenKey(const GrCustomStage& s,
+                                                       const GrGLCaps& caps) {
+    return 0;
+}
+
+/////////////////////////////////////////////////////////////////////
+
+GR_DEFINE_CUSTOM_STAGE_TEST(GrMagnifierEffect);
+
+GrCustomStage* GrMagnifierEffect::TestCreate(SkRandom* random,
+                                             GrContext* context,
+                                             GrTexture** textures) {
+    const int kMaxWidth = 200;
+    const int kMaxHeight = 200;
+    const int kMaxInset = 20;
+    SkScalar width = random->nextULessThan(kMaxWidth);
+    SkScalar height = random->nextULessThan(kMaxHeight);
+    SkScalar x = random->nextULessThan(kMaxWidth - width);
+    SkScalar y = random->nextULessThan(kMaxHeight - height);
+    SkScalar inset = random->nextULessThan(kMaxInset);
+
+    SkAutoTUnref<SkImageFilter> filter(
+            new SkMagnifierImageFilter(
+                SkRect::MakeXYWH(x, y, width, height),
+                inset));
+    GrSamplerState sampler;
+    GrCustomStage* stage;
+    filter->asNewCustomStage(&stage, textures[0]);
+    GrAssert(NULL != stage);
+    return stage;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+const GrProgramStageFactory& GrMagnifierEffect::getFactory() const {
+    return GrTProgramStageFactory<GrMagnifierEffect>::getInstance();
+}
+
+bool GrMagnifierEffect::isEqual(const GrCustomStage& sBase) const {
+     const GrMagnifierEffect& s =
+        static_cast<const GrMagnifierEffect&>(sBase);
+    return (this->fXOffset == s.fXOffset &&
+            this->fYOffset == s.fYOffset &&
+            this->fXZoom == s.fXZoom &&
+            this->fYZoom == s.fYZoom &&
+            this->fXInset == s.fXInset &&
+            this->fYInset == s.fYInset);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+SkMagnifierImageFilter::SkMagnifierImageFilter(SkFlattenableReadBuffer& buffer)
+  : INHERITED(buffer) {
+    float x = buffer.readScalar();
+    float y = buffer.readScalar();
+    float width = buffer.readScalar();
+    float height = buffer.readScalar();
+    fSrcRect = SkRect::MakeXYWH(x, y, width, height);
+    fInset = buffer.readScalar();
+}
+
+SkMagnifierImageFilter::SkMagnifierImageFilter(SkRect srcRect, SkScalar inset)
+    : fSrcRect(srcRect), fInset(inset) {
+    SkASSERT(srcRect.x() >= 0 && srcRect.y() >= 0 && inset >= 0);
+}
+
+bool SkMagnifierImageFilter::asNewCustomStage(GrCustomStage** stage,
+                                              GrTexture* texture) const {
+    if (stage) {
+      *stage =
+          SkNEW_ARGS(GrMagnifierEffect, (texture,
+                                         fSrcRect.x() / texture->width(),
+                                         fSrcRect.y() / texture->height(),
+                                         texture->width() / fSrcRect.width(),
+                                         texture->height() / fSrcRect.height(),
+                                         fInset / texture->width(),
+                                         fInset / texture->height()));
+    }
+    return true;
+}
+
+void SkMagnifierImageFilter::flatten(SkFlattenableWriteBuffer& buffer) const {
+    this->INHERITED::flatten(buffer);
+    buffer.writeScalar(fSrcRect.x());
+    buffer.writeScalar(fSrcRect.y());
+    buffer.writeScalar(fSrcRect.width());
+    buffer.writeScalar(fSrcRect.height());
+    buffer.writeScalar(fInset);
+}
+
+bool SkMagnifierImageFilter::onFilterImage(Proxy*, const SkBitmap& src,
+                                           const SkMatrix&, SkBitmap* dst,
+                                           SkIPoint* offset) {
+    SkASSERT(src.config() == SkBitmap::kARGB_8888_Config);
+    SkASSERT(fSrcRect.width() < src.width());
+    SkASSERT(fSrcRect.height() < src.height());
+
+    if (src.config() != SkBitmap::kARGB_8888_Config) {
+      return false;
+    }
+
+    SkAutoLockPixels alp(src);
+    SkASSERT(src.getPixels());
+    if (!src.getPixels() || src.width() <= 0 || src.height() <= 0) {
+      return false;
+    }
+
+    float inv_inset = fInset > 0 ? 1.0f / SkScalarToFloat(fInset) : 1.0f;
+
+    float inv_x_zoom = fSrcRect.width() / src.width();
+    float inv_y_zoom = fSrcRect.height() / src.height();
+
+    dst->setConfig(src.config(), src.width(), src.height());
+    dst->allocPixels();
+    SkColor* sptr = src.getAddr32(0, 0);
+    SkColor* dptr = dst->getAddr32(0, 0);
+    int width = src.width(), height = src.height();
+    for (int y = 0; y < height; ++y) {
+        for (int x = 0; x < width; ++x) {
+            float x_dist = std::min(x, width - x - 1) * inv_inset;
+            float y_dist = std::min(y, height - y - 1) * inv_inset;
+            float weight = 0;
+
+            // To create a smooth curve at the corners, we need to work on
+            // a square twice the size of the inset.
+            if (x_dist < 2 && y_dist < 2) {
+                x_dist = 2 - x_dist;
+                y_dist = 2 - y_dist;
+
+                float dist = sqrt(x_dist * x_dist + y_dist * y_dist);
+                dist = std::max(2 - dist, 0.0f);
+                weight = std::min(dist * dist, 1.0f);
+            } else {
+                float sq_dist = std::min(x_dist * x_dist, y_dist * y_dist);
+                weight = std::min(sq_dist, 1.0f);
+            }
+
+            int x_val = weight * (fSrcRect.x() + x * inv_x_zoom) +
+                        (1 - weight) * x;
+            int y_val = weight * (fSrcRect.y() + y * inv_y_zoom) +
+                        (1 - weight) * y;
+
+            x_val = std::min(x_val, width - 1);
+            y_val = std::min(y_val, height - 1);
+
+            *dptr = sptr[y_val * width + x_val];
+            dptr++;
+        }
+    }
+    return true;
+}
+
+SK_DEFINE_FLATTENABLE_REGISTRAR(SkMagnifierImageFilter)
diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index 592cdfc6e6..2d6d3a2e0f 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -1966,4 +1966,3 @@ SkGpuDevice::SkGpuDevice(GrContext* context,
     fCache = cacheEntry;
     fNeedClear = needClear;
 }
-
diff --git a/src/ports/SkGlobalInitialization_chromium.cpp b/src/ports/SkGlobalInitialization_chromium.cpp
index 08e83dc05d..071f84a9e6 100644
--- a/src/ports/SkGlobalInitialization_chromium.cpp
+++ b/src/ports/SkGlobalInitialization_chromium.cpp
@@ -15,6 +15,7 @@
 #include "SkLayerDrawLooper.h"
 #include "SkMallocPixelRef.h"
 #include "SkXfermode.h"
+#include "SkZoomImageFilter.h"
 
 void SkFlattenable::InitializeFlattenables() {
 
@@ -24,6 +25,7 @@ void SkFlattenable::InitializeFlattenables() {
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkDashPathEffect)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkLayerDrawLooper)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkMallocPixelRef)
+    SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkZoomImageFilter)
 
     SkBlurMaskFilter::InitializeFlattenables();
     SkColorFilter::InitializeFlattenables();
diff --git a/src/ports/SkGlobalInitialization_default.cpp b/src/ports/SkGlobalInitialization_default.cpp
index 69984a3406..9b7a74a00a 100644
--- a/src/ports/SkGlobalInitialization_default.cpp
+++ b/src/ports/SkGlobalInitialization_default.cpp
@@ -45,6 +45,7 @@
 #include "SkStippleMaskFilter.h"
 #include "SkTableColorFilter.h"
 #include "SkTestImageFilters.h"
+#include "SkZoomImageFilter.h"
 
 void SkFlattenable::InitializeFlattenables() {
 
@@ -71,6 +72,7 @@ void SkFlattenable::InitializeFlattenables() {
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkPixelXorXfermode)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkStippleMaskFilter)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkSumPathEffect)
+    SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkMagnifierImageFilter)
 
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkOffsetImageFilter)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkComposeImageFilter)