1 files changed, 173 insertions, 0 deletions
diff --git a/gfx/layers/composite/TextRenderer.cpp b/gfx/layers/composite/TextRenderer.cpp
new file mode 100644
index 000000000..be59cb246
--- /dev/null
+++ b/gfx/layers/composite/TextRenderer.cpp
@@ -0,0 +1,173 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "TextRenderer.h"
+#include "FontData.h"
+#include "png.h"
+#include "mozilla/Base64.h"
+#include "mozilla/layers/Compositor.h"
+#include "mozilla/layers/TextureHost.h"
+#include "mozilla/layers/Effects.h"
+
+namespace mozilla {
+namespace layers {
+
+using namespace gfx;
+using namespace std;
+
+const Float sBackgroundOpacity = 0.6f;
+const SurfaceFormat sTextureFormat = SurfaceFormat::B8G8R8A8;
+
+static void PNGAPI info_callback(png_structp png_ptr, png_infop info_ptr)
+{
+  png_read_update_info(png_ptr, info_ptr);
+}
+
+static void PNGAPI row_callback(png_structp png_ptr, png_bytep new_row, png_uint_32 row_num, int pass)
+{
+  MOZ_ASSERT(sTextureFormat == SurfaceFormat::B8G8R8A8);
+
+  DataSourceSurface::MappedSurface map = static_cast<TextRenderer*>(png_get_progressive_ptr(png_ptr))->GetSurfaceMap();
+
+  uint32_t* dst = (uint32_t*)(map.mData + map.mStride * row_num);
+
+  for (uint32_t x = 0; x < sTextureWidth; x++) {
+    // We blend to a transparent white background, this will make text readable
+    // even if it's on a dark background. Without hurting our ability to
+    // interact with the content behind the text.
+    Float alphaValue = Float(0xFF - new_row[x]) / 255.0f;
+    Float baseValue = sBackgroundOpacity * (1.0f - alphaValue);
+    Color pixelColor(baseValue, baseValue, baseValue, baseValue + alphaValue);
+    dst[x] = pixelColor.ToABGR();
+  }
+}
+
+TextRenderer::~TextRenderer()
+{
+  if (mGlyphBitmaps) {
+    mGlyphBitmaps->Unmap();
+  }
+}
+
+void
+TextRenderer::RenderText(const string& aText, const IntPoint& aOrigin,
+                         const Matrix4x4& aTransform, uint32_t aTextSize,
+                         uint32_t aTargetPixelWidth)
+{
+  EnsureInitialized();
+
+  // For now we only have a bitmap font with a 16px cell size, so we just
+  // scale it up if the user wants larger text.
+  Float scaleFactor = Float(aTextSize) / Float(sCellHeight);
+
+  aTargetPixelWidth /= scaleFactor;
+
+  uint32_t numLines = 1;
+  uint32_t maxWidth = 0;
+  uint32_t lineWidth = 0;
+  // Calculate the size of the surface needed to draw all the glyphs.
+  for (uint32_t i = 0; i < aText.length(); i++) {
+    // Insert a line break if we go past the TargetPixelWidth.
+    // XXX - this has the downside of overrunning the intended width, causing
+    // things at the edge of a window to be cut off.
+    if (aText[i] == '\n' || (aText[i] == ' ' && lineWidth > aTargetPixelWidth)) {
+      numLines++;
+      lineWidth = 0;
+      continue;
+    }
+
+    lineWidth += sGlyphWidths[uint32_t(aText[i])];
+    maxWidth = std::max(lineWidth, maxWidth);
+  }
+
+  // Create a surface to draw our glyphs to.
+  RefPtr<DataSourceSurface> textSurf =
+    Factory::CreateDataSourceSurface(IntSize(maxWidth, numLines * sCellHeight), sTextureFormat);
+  if (NS_WARN_IF(!textSurf)) {
+    return;
+  }
+
+  DataSourceSurface::MappedSurface map;
+  if (NS_WARN_IF(!textSurf->Map(DataSourceSurface::MapType::READ_WRITE, &map))) {
+    return;
+  }
+
+  // Initialize the surface to transparent white.
+  memset(map.mData, uint8_t(sBackgroundOpacity * 255.0f),
+         numLines * sCellHeight * map.mStride);
+
+  uint32_t currentXPos = 0;
+  uint32_t currentYPos = 0;
+
+  // Copy our glyphs onto the surface.
+  for (uint32_t i = 0; i < aText.length(); i++) {
+    if (aText[i] == '\n' || (aText[i] == ' ' && currentXPos > aTargetPixelWidth)) {
+      currentYPos += sCellHeight;
+      currentXPos = 0;
+      continue;
+    }
+
+    uint32_t glyphXOffset = aText[i] % (sTextureWidth / sCellWidth) * sCellWidth * BytesPerPixel(sTextureFormat);
+    uint32_t truncatedLine = aText[i] / (sTextureWidth / sCellWidth);
+    uint32_t glyphYOffset =  truncatedLine * sCellHeight * mMap.mStride;
+
+    for (int y = 0; y < 16; y++) {
+      memcpy(map.mData + (y + currentYPos) * map.mStride + currentXPos * BytesPerPixel(sTextureFormat),
+             mMap.mData + glyphYOffset + y * mMap.mStride + glyphXOffset,
+             sGlyphWidths[uint32_t(aText[i])] * BytesPerPixel(sTextureFormat));
+    }
+
+    currentXPos += sGlyphWidths[uint32_t(aText[i])];
+  }
+
+  textSurf->Unmap();
+
+  RefPtr<DataTextureSource> src = mCompositor->CreateDataTextureSource();
+
+  if (!src->Update(textSurf)) {
+    // Upload failed.
+    return;
+  }
+
+  RefPtr<EffectRGB> effect = new EffectRGB(src, true, SamplingFilter::LINEAR);
+  EffectChain chain;
+  chain.mPrimaryEffect = effect;
+
+  Matrix4x4 transform = aTransform;
+  transform.PreScale(scaleFactor, scaleFactor, 1.0f);
+  mCompositor->DrawQuad(Rect(aOrigin.x, aOrigin.y, maxWidth, numLines * 16),
+                        IntRect(-10000, -10000, 20000, 20000), chain, 1.0f, transform);
+}
+
+void
+TextRenderer::EnsureInitialized()
+{
+  if (mGlyphBitmaps) {
+    return;
+  }
+
+  mGlyphBitmaps = Factory::CreateDataSourceSurface(IntSize(sTextureWidth, sTextureHeight), sTextureFormat);
+  if (NS_WARN_IF(!mGlyphBitmaps)) {
+    return;
+  }
+
+  if (NS_WARN_IF(!mGlyphBitmaps->Map(DataSourceSurface::MapType::READ_WRITE, &mMap))) {
+    return;
+  }
+
+  png_structp png_ptr = NULL;
+  png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
+
+  png_set_progressive_read_fn(png_ptr, this, info_callback, row_callback, nullptr);
+  png_infop info_ptr = NULL;
+  info_ptr = png_create_info_struct(png_ptr);
+
+  png_process_data(png_ptr, info_ptr, (uint8_t*)sFontPNG, sizeof(sFontPNG));
+
+  png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
+}
+
+} // namespace layers
+} // namespace mozilla