Implement GL support for buffer textures

src/gpu/gl/GrGLGpu.cpp

Index: src/gpu/gl/GrGLGpu.cpp
diff --git a/src/gpu/gl/GrGLGpu.cpp b/src/gpu/gl/GrGLGpu.cpp
index 76cb1a068a2bc3dee7ae2df28bc167d1eda2aad9..21adb4abdad98816b94212d8c87653b33c5a8bbe 100644
--- a/src/gpu/gl/GrGLGpu.cpp
+++ b/src/gpu/gl/GrGLGpu.cpp
@@ -582,6 +582,26 @@ GrTexture* GrGLGpu::onWrapBackendTexture(const GrBackendTextureDesc& desc,
         if (!this->glCaps().rectangleTextureSupport()) {
             return nullptr;
         }
+    } else if (GR_GL_TEXTURE_BUFFER == idDesc.fInfo.fTarget) {
+        if (!this->glCaps().glslCaps()->bufferTextureSupport()) {
+            SkDEBUGFAIL("Buffer textures are not supported.");
+            return nullptr;
+        }
+        if (renderTarget) {
+            SkDEBUGFAIL("Rendering to a buffer texture is not supported.");
+            return nullptr;
+        }
+        if (0 != desc.fHeight) {
+            // This texture is just a 1-dimensional window into a buffer object. It has no height
+            // and its GPU memory size is effectively zero, because the actual memory is attributed
+            // to the buffer object itself.
+            SkDEBUGFAIL("Buffer textures must have a height of 0.");
+            return nullptr;
+        }
+        if (0 != desc.fSampleCnt) {
+            SkDEBUGFAIL("Multisampled buffer textures are not supported.");
+            return nullptr;
+        }
     } else if (GR_GL_TEXTURE_2D != idDesc.fInfo.fTarget) {
         return nullptr;
     }
@@ -2102,8 +2122,12 @@ bool GrGLGpu::flushGLState(const GrPipeline& pipeline, const GrPrimitiveProcesso
 
     int numTextureAccesses = textureAccesses.count();
     for (int i = 0; i < numTextureAccesses; i++) {
-        this->bindTexture(i, textureAccesses[i]->getParams(),
-                          static_cast<GrGLTexture*>(textureAccesses[i]->getTexture()));
+        GrGLTexture* texture = static_cast<GrGLTexture*>(textureAccesses[i]->getTexture());
+        if (!texture->supportsTextureParams()) {
+            this->bindTexture(i, texture);
+        } else {
+            this->flushTexture(i, textureAccesses[i]->getParams(), texture);
+        }
     }
 
     GrGLRenderTarget* glRT = static_cast<GrGLRenderTarget*>(pipeline.getRenderTarget());
@@ -3271,6 +3295,24 @@ void GrGLGpu::flushBlend(const GrXferProcessor::BlendInfo& blendInfo, const GrSw
     }
 }
 
+void GrGLGpu::bindTexture(int unitIdx, GrGLTexture* texture) {
+    SkASSERT(texture);
+
+    // If we created a rt/tex and rendered to it without using a texture and now we're texturing
+    // from the rt it will still be the last bound texture, but it needs resolving. So keep this
+    // out of the "last != next" check.
+    GrGLRenderTarget* texRT = static_cast<GrGLRenderTarget*>(texture->asRenderTarget());
+    if (texRT) {
+        this->onResolveRenderTarget(texRT);
+    }
+
+    if (fHWBoundTextureUniqueIDs[unitIdx] != texture->getUniqueID()) {
+        this->setTextureUnit(unitIdx);
+        GL_CALL(BindTexture(texture->target(), texture->textureID()));
+        fHWBoundTextureUniqueIDs[unitIdx] = texture->getUniqueID();
+    }
+}
+
 static inline GrGLenum tile_to_gl_wrap(SkShader::TileMode tm) {
     static const GrGLenum gWrapModes[] = {
         GR_GL_CLAMP_TO_EDGE,
@@ -3311,8 +3353,8 @@ static void get_tex_param_swizzle(GrPixelConfig config,
     }
 }
 
-void GrGLGpu::bindTexture(int unitIdx, const GrTextureParams& params, GrGLTexture* texture) {
-    SkASSERT(texture);
+void GrGLGpu::flushTexture(int unitIdx, const GrTextureParams& params, GrGLTexture* texture) {
+    this->bindTexture(unitIdx, texture);
 
 #ifdef SK_DEBUG
     if (!this->caps()->npotTextureTileSupport()) {
@@ -3326,22 +3368,6 @@ void GrGLGpu::bindTexture(int unitIdx, const GrTextureParams& params, GrGLTextur
     }
 #endif
 
-    // If we created a rt/tex and rendered to it without using a texture and now we're texturing
-    // from the rt it will still be the last bound texture, but it needs resolving. So keep this
-    // out of the "last != next" check.
-    GrGLRenderTarget* texRT = static_cast<GrGLRenderTarget*>(texture->asRenderTarget());
-    if (texRT) {
-        this->onResolveRenderTarget(texRT);
-    }
-
-    uint32_t textureID = texture->getUniqueID();
-    GrGLenum target = texture->target();
-    if (fHWBoundTextureUniqueIDs[unitIdx] != textureID) {
-        this->setTextureUnit(unitIdx);
-        GL_CALL(BindTexture(target, texture->textureID()));
-        fHWBoundTextureUniqueIDs[unitIdx] = textureID;
-    }
-
     ResetTimestamp timestamp;
     const GrGLTexture::TexParams& oldTexParams = texture->getCachedTexParams(&timestamp);
     bool setAll = timestamp < this->getResetTimestamp();
@@ -3357,7 +3383,9 @@ void GrGLGpu::bindTexture(int unitIdx, const GrTextureParams& params, GrGLTextur
         GR_GL_LINEAR,
         GR_GL_LINEAR
     };
+
     GrTextureParams::FilterMode filterMode = params.filterMode();
+    GrGLenum target = texture->target();
 
     if (GrTextureParams::kMipMap_FilterMode == filterMode) {
         if (!this->caps()->mipMapSupport() || GrPixelConfigIsCompressed(texture->config())) {
@@ -3798,7 +3826,7 @@ void GrGLGpu::createCopyPrograms() {
             "  %s = %s(u_texture, v_texCoord);"
             "}",
             fsOutName,
-            GrGLSLTexture2DFunctionName(kVec2f_GrSLType, kSamplerTypes[i], this->glslGeneration())
+            GrGLSLTextureFunctionName(kVec2f_GrSLType, kSamplerTypes[i], this->glslGeneration())
         );
 
         GL_CALL_RET(fCopyPrograms[i].fProgram, CreateProgram());
@@ -4014,7 +4042,7 @@ void GrGLGpu::copySurfaceAsDraw(GrSurface* dst,
 
     GrGLTexture* srcTex = static_cast<GrGLTexture*>(src->asTexture());
     GrTextureParams params(SkShader::kClamp_TileMode, GrTextureParams::kNone_FilterMode);
-    this->bindTexture(0, params, srcTex);
+    this->flushTexture(0, params, srcTex);
 
     GrGLIRect dstVP;
     this->bindSurfaceFBOForCopy(dst, GR_GL_FRAMEBUFFER, &dstVP, kDst_TempFBOTarget);