Utilities for creating texture backed SkImages. (#2829)

flow/BUILD.gn

@@ -38,8 +38,11 @@ source_set("flow") {
     "layers/shader_mask_layer.h",
     "layers/transform_layer.cc",
     "layers/transform_layer.h",
+    "open_gl.h",
     "raster_cache.cc",
     "raster_cache.h",
+    "texture_image.cc",
+    "texture_image.h",
   ]
 
   deps = [

flow/open_gl.h

@@ -0,0 +1,28 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLOW_OPEN_GL_H_
+#define FLOW_OPEN_GL_H_
+
+#include "build/build_config.h"
+
+#if OS_IOS
+
+#include <OpenGLES/ES2/gl.h>
+
+#elif OS_MACOSX
+
+#include <OpenGL/gl.h>
+
+#elif OS_ANDROID
+
+#include <GLES2/gl2.h>
+
+#else
+
+#error OpenGL headers not found for this platform.
+
+#endif
+
+#endif  // FLOW_OPEN_GL_H_

flow/texture_image.cc

@@ -0,0 +1,92 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flow/texture_image.h"
+#include "flow/open_gl.h"
+
+namespace flow {
+
+inline GLint ToGLFormat(TextureImageFormat format) {
+  switch (format) {
+    case TextureImageFormat::RGBA:
+      return GL_RGBA;
+    case TextureImageFormat::RGB:
+      return GL_RGB;
+    case TextureImageFormat::Grey:
+      return GL_LUMINANCE;
+    case TextureImageFormat::GreyAlpha:
+      return GL_LUMINANCE_ALPHA;
+  }
+  return GL_NONE;
+}
+
+inline GLint ToGLDataFormat(TextureImageDataFormat dataFormat) {
+  switch (dataFormat) {
+    case TextureImageDataFormat::UnsignedByte:
+      return GL_UNSIGNED_BYTE;
+    case TextureImageDataFormat::UnsignedShort565:
+      return GL_UNSIGNED_SHORT_5_6_5;
+  }
+  return GL_NONE;
+}
+
+sk_sp<SkImage> TextureImageCreate(GrContext* context,
+                                  TextureImageFormat format,
+                                  const SkISize& size,
+                                  TextureImageDataFormat dataFormat,
+                                  const uint8_t* data) {
+  GLuint handle = GL_NONE;
+
+  // Generate the texture handle.
+  glGenTextures(1, &handle);
+
+  // Bind the texture.
+  glBindTexture(GL_TEXTURE_2D, handle);
+
+  // Specify default texture properties.
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+  // Update unpack alignment based on format.
+  glPixelStorei(GL_UNPACK_ALIGNMENT,
+                dataFormat == TextureImageDataFormat::UnsignedByte ? 4 : 2);
+
+  GLint gl_format = ToGLFormat(format);
+
+  // Upload the texture.
+  glTexImage2D(GL_TEXTURE_2D,               // target
+               0,                           // level
+               gl_format,                   // internal format
+               size.fWidth,                 // width
+               size.fHeight,                // height
+               0,                           // border
+               gl_format,                   // format
+               ToGLDataFormat(dataFormat),  // format
+               data);
+
+  // Clear the binding. We are done.
+  glBindTexture(GL_TEXTURE_2D, GL_NONE);
+
+  // Create an SkImage handle from the texture.
+  GrBackendTextureDesc desc;
+
+  desc.fWidth = size.fWidth;
+  desc.fHeight = size.fHeight;
+  desc.fTextureHandle = handle;
+
+  if (auto image = SkImage::MakeFromAdoptedTexture(context, desc)) {
+    // Texture handle was successfully adopted by the SkImage.
+    return image;
+  }
+
+  // We could not create an SkImage from the texture. Since it could not be
+  // adopted, delete the handle and return null.
+  glDeleteTextures(1, &handle);
+
+  return nullptr;
+}
+
+}  // namespace flow

flow/texture_image.h

@@ -0,0 +1,33 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLOW_TEXTURE_IMAGE_H_
+#define FLOW_TEXTURE_IMAGE_H_
+
+#include "base/macros.h"
+#include "third_party/skia/include/core/SkImage.h"
+
+namespace flow {
+
+enum class TextureImageFormat {
+  Grey,
+  GreyAlpha,
+  RGB,
+  RGBA,
+};
+
+enum class TextureImageDataFormat {
+  UnsignedByte,
+  UnsignedShort565,
+};
+
+sk_sp<SkImage> TextureImageCreate(GrContext* context,
+                                  TextureImageFormat format,
+                                  const SkISize& size,
+                                  TextureImageDataFormat dataFormat,
+                                  const uint8_t* data);
+
+}  // namespace flow
+
+#endif  // FLOW_TEXTURE_IMAGE_H_