Allow custom GrAtlasGlyphCache texture sizes

A single glyph cache size doesn't make sense across the hardware Skia
runs on. This change allows a custom size to be specified (via a byte
limit), allowing cache size to be customized at context creation time.

Bug: 717178
Change-Id: I4f7baddd1897b2eac4f6d6e4fff1f805e1cdd250
Reviewed-on: https://skia-review.googlesource.com/15135
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>

3 files changed, 44 insertions, 27 deletions

diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index 2d46b5c02b..fc38dfa9b8 100644
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -109,7 +109,7 @@ void GrContext::initCommon(const GrContextOptions& options) {
     fDrawingManager.reset(new GrDrawingManager(this, prcOptions,
                                                options.fImmediateMode, &fSingleOwner));
 
-    fAtlasGlyphCache = new GrAtlasGlyphCache(this);
+    fAtlasGlyphCache = new GrAtlasGlyphCache(this, options.fGlyphCacheTextureMaximumBytes);
 
     fTextBlobCache.reset(new GrTextBlobCache(TextBlobCacheOverBudgetCB, this));
 }
diff --git a/src/gpu/text/GrAtlasGlyphCache.cpp b/src/gpu/text/GrAtlasGlyphCache.cpp
index 0b364f43fe..39c3e10ca5 100644
--- a/src/gpu/text/GrAtlasGlyphCache.cpp
+++ b/src/gpu/text/GrAtlasGlyphCache.cpp
@@ -36,31 +36,48 @@ bool GrAtlasGlyphCache::initAtlas(GrMaskFormat format) {
     return true;
 }
 
-GrAtlasGlyphCache::GrAtlasGlyphCache(GrContext* context)
-    : fContext(context)
-    , fPreserveStrike(nullptr) {
-
-    // setup default atlas configs
-    fAtlasConfigs[kA8_GrMaskFormat].fWidth = 2048;
-    fAtlasConfigs[kA8_GrMaskFormat].fHeight = 2048;
-    fAtlasConfigs[kA8_GrMaskFormat].fLog2Width = 11;
-    fAtlasConfigs[kA8_GrMaskFormat].fLog2Height = 11;
-    fAtlasConfigs[kA8_GrMaskFormat].fPlotWidth = 512;
-    fAtlasConfigs[kA8_GrMaskFormat].fPlotHeight = 256;
-
-    fAtlasConfigs[kA565_GrMaskFormat].fWidth = 1024;
-    fAtlasConfigs[kA565_GrMaskFormat].fHeight = 2048;
-    fAtlasConfigs[kA565_GrMaskFormat].fLog2Width = 10;
-    fAtlasConfigs[kA565_GrMaskFormat].fLog2Height = 11;
-    fAtlasConfigs[kA565_GrMaskFormat].fPlotWidth = 256;
-    fAtlasConfigs[kA565_GrMaskFormat].fPlotHeight = 256;
-
-    fAtlasConfigs[kARGB_GrMaskFormat].fWidth = 1024;
-    fAtlasConfigs[kARGB_GrMaskFormat].fHeight = 2048;
-    fAtlasConfigs[kARGB_GrMaskFormat].fLog2Width = 10;
-    fAtlasConfigs[kARGB_GrMaskFormat].fLog2Height = 11;
-    fAtlasConfigs[kARGB_GrMaskFormat].fPlotWidth = 256;
-    fAtlasConfigs[kARGB_GrMaskFormat].fPlotHeight = 256;
+GrAtlasGlyphCache::GrAtlasGlyphCache(GrContext* context, float maxTextureBytes)
+        : fContext(context), fPreserveStrike(nullptr) {
+    // Calculate RGBA size. Must be between 1024 x 512 and MaxTextureSize x MaxTextureSize / 2
+    int log2MaxTextureSize = log2(context->caps()->maxTextureSize());
+    int log2MaxDim = 10;
+    for (; log2MaxDim <= log2MaxTextureSize; ++log2MaxDim) {
+        int maxDim = 1 << log2MaxDim;
+        int minDim = 1 << (log2MaxDim - 1);
+
+        if (maxDim * minDim * 4 >= maxTextureBytes) break;
+    }
+
+    int log2MinDim = log2MaxDim - 1;
+    int maxDim = 1 << log2MaxDim;
+    int minDim = 1 << log2MinDim;
+    // Plots are either 256 or 512.
+    int maxPlot = SkTMin(512, SkTMax(256, 1 << (log2MaxDim - 2)));
+    int minPlot = SkTMin(512, SkTMax(256, 1 << (log2MaxDim - 3)));
+
+    // Setup default atlas configs. The A8 atlas uses maxDim for both width and height, as the A8
+    // format is already very compact.
+    fAtlasConfigs[kA8_GrMaskFormat].fWidth = maxDim;
+    fAtlasConfigs[kA8_GrMaskFormat].fHeight = maxDim;
+    fAtlasConfigs[kA8_GrMaskFormat].fLog2Width = log2MaxDim;
+    fAtlasConfigs[kA8_GrMaskFormat].fLog2Height = log2MaxDim;
+    fAtlasConfigs[kA8_GrMaskFormat].fPlotWidth = maxPlot;
+    fAtlasConfigs[kA8_GrMaskFormat].fPlotHeight = minPlot;
+
+    // A565 and ARGB use maxDim x minDim.
+    fAtlasConfigs[kA565_GrMaskFormat].fWidth = minDim;
+    fAtlasConfigs[kA565_GrMaskFormat].fHeight = maxDim;
+    fAtlasConfigs[kA565_GrMaskFormat].fLog2Width = log2MinDim;
+    fAtlasConfigs[kA565_GrMaskFormat].fLog2Height = log2MaxDim;
+    fAtlasConfigs[kA565_GrMaskFormat].fPlotWidth = minPlot;
+    fAtlasConfigs[kA565_GrMaskFormat].fPlotHeight = minPlot;
+
+    fAtlasConfigs[kARGB_GrMaskFormat].fWidth = minDim;
+    fAtlasConfigs[kARGB_GrMaskFormat].fHeight = maxDim;
+    fAtlasConfigs[kARGB_GrMaskFormat].fLog2Width = log2MinDim;
+    fAtlasConfigs[kARGB_GrMaskFormat].fLog2Height = log2MaxDim;
+    fAtlasConfigs[kARGB_GrMaskFormat].fPlotWidth = minPlot;
+    fAtlasConfigs[kARGB_GrMaskFormat].fPlotHeight = minPlot;
 }
 
 GrAtlasGlyphCache::~GrAtlasGlyphCache() {
diff --git a/src/gpu/text/GrAtlasGlyphCache.h b/src/gpu/text/GrAtlasGlyphCache.h
index a75600b615..3ebea2b72b 100644
--- a/src/gpu/text/GrAtlasGlyphCache.h
+++ b/src/gpu/text/GrAtlasGlyphCache.h
@@ -110,7 +110,7 @@ private:
  */
 class GrAtlasGlyphCache {
 public:
-    GrAtlasGlyphCache(GrContext*);
+    GrAtlasGlyphCache(GrContext*, float maxTextureBytes);
     ~GrAtlasGlyphCache();
     // The user of the cache may hold a long-lived ref to the returned strike. However, actions by
     // another client of the cache may cause the strike to be purged while it is still reffed.