Reopened: Caching the result of readPixelsSupported

src/gpu/gl/GrGLCaps.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGLCaps.h"
 #include "GrGLContext.h"
@@ skipping 32 matching lines @@
     fTwoFormatLimit = false;
     fFragCoordsConventionSupport = false;
     fVertexArrayObjectSupport = false;
     fUseNonVBOVertexAndIndexDynamicData = false;
     fIsCoreProfile = false;
     fFullClearIsFree = false;
     fDropsTileOnZeroDivide = false;
     fFBFetchSupport = false;
     fFBFetchColorName = NULL;
     fFBFetchExtensionString = NULL;
+
+    fReadPixelsSupportedCache.reset();
 }
 
 GrGLCaps::GrGLCaps(const GrGLCaps& caps) : GrDrawTargetCaps() {
     *this = caps;
 }
 
 GrGLCaps& GrGLCaps::operator= (const GrGLCaps& caps) {
     INHERITED::operator=(caps);
     fVerifiedColorConfigs = caps.fVerifiedColorConfigs;
     fStencilFormats = caps.fStencilFormats;
@@ skipping 512 matching lines @@
     fLATCAlias = alias;
 
     // Check for R11_EAC ... We don't support R11_EAC on desktop, as most
     // cards default to decompressing the textures in the driver, and is
     // generally slower.
     if (kGL_GrGLStandard != standard) {
         fConfigTextureSupport[kR11_EAC_GrPixelConfig] = version >= GR_GL_VER(3, 0);
     }
 
     // Check for ASTC
-    fConfigTextureSupport[kASTC_12x12_GrPixelConfig] = 
+    fConfigTextureSupport[kASTC_12x12_GrPixelConfig] =
         ctxInfo.hasExtension("GL_KHR_texture_compression_astc_hdr") ||
         ctxInfo.hasExtension("GL_KHR_texture_compression_astc_ldr") ||
         ctxInfo.hasExtension("GL_OES_texture_compression_astc");
 
     // Check for floating point texture support
     // NOTE: We disallow floating point textures on ES devices if linear
     // filtering modes are not supported.  This is for simplicity, but a more
     // granular approach is possible.  Coincidentally, floating point textures became part of
     // the standard in ES3.1 / OGL 3.1, hence the shorthand
     bool hasFPTextures = version >= GR_GL_VER(3, 1);
     if (!hasFPTextures) {
         hasFPTextures = ctxInfo.hasExtension("GL_ARB_texture_float") ||
                         (ctxInfo.hasExtension("OES_texture_float_linear") &&
                          ctxInfo.hasExtension("GL_OES_texture_float"));
     }
     fConfigTextureSupport[kRGBA_float_GrPixelConfig] = hasFPTextures;
 }
 
-bool GrGLCaps::readPixelsSupported(const GrGLInterface* intf,
-                                   GrGLenum format,
-                                   GrGLenum type) const {
+bool GrGLCaps::doReadPixelsSupported(const GrGLInterface* intf,
+                                     GrGLenum format,
+                                     GrGLenum type) const {
     if (GR_GL_RGBA == format && GR_GL_UNSIGNED_BYTE == type) {
         // ES 2 guarantees this format is supported
         return true;
     }
 
     if (!fTwoFormatLimit) {
         // not limited by ES 2's constraints
         return true;
     }
 
     GrGLint otherFormat = GR_GL_RGBA;
     GrGLint otherType = GR_GL_UNSIGNED_BYTE;
 
     // The other supported format/type combo supported for ReadPixels
     // can change based on which render target is bound
     GR_GL_GetIntegerv(intf,
                       GR_GL_IMPLEMENTATION_COLOR_READ_FORMAT,
                       &otherFormat);
 
     GR_GL_GetIntegerv(intf,
                       GR_GL_IMPLEMENTATION_COLOR_READ_TYPE,
                       &otherType);
 
     return (GrGLenum)otherFormat == format && (GrGLenum)otherType == type;
 }
 
+bool GrGLCaps::readPixelsSupported(const GrGLInterface* intf,
+                                   GrGLenum format,
+                                   GrGLenum type,
+                                   GrGLenum currFboFormat) const {
+
+    ReadPixelsSupportedFormats::Key key = {format, type, currFboFormat};
+
+    ReadPixelsSupportedFormats* cachedValue = fReadPixelsSupportedCache.find(key);
+
+    if (NULL == cachedValue) {
+        bool value = doReadPixelsSupported(intf, format, type);
+        ReadPixelsSupportedFormats newValue(key, value);
+        fReadPixelsSupportedCache.add(newValue);
+
+        return newValue.value();
+    }
+
+    return cachedValue->value();
+}
+
 void GrGLCaps::initFSAASupport(const GrGLContextInfo& ctxInfo, const GrGLInterface* gli) {
 
     fMSFBOType = kNone_MSFBOType;
     if (kGL_GrGLStandard != ctxInfo.standard()) {
         // We prefer the EXT/IMG extension over ES3 MSAA because we've observed
         // ES3 driver bugs on at least one device with a tiled GPU (N10).
         if (ctxInfo.hasExtension("GL_EXT_multisampled_render_to_texture")) {
             fMSFBOType = kES_EXT_MsToTexture_MSFBOType;
         } else if (ctxInfo.hasExtension("GL_IMG_multisampled_render_to_texture")) {
             fMSFBOType = kES_IMG_MsToTexture_MSFBOType;
@@ skipping 198 matching lines @@
     r.appendf("Two Format Limit: %s\n", (fTwoFormatLimit ? "YES": "NO"));
     r.appendf("Fragment coord conventions support: %s\n",
              (fFragCoordsConventionSupport ? "YES": "NO"));
     r.appendf("Vertex array object support: %s\n", (fVertexArrayObjectSupport ? "YES": "NO"));
     r.appendf("Use non-VBO for dynamic data: %s\n",
              (fUseNonVBOVertexAndIndexDynamicData ? "YES" : "NO"));
     r.appendf("Full screen clear is free: %s\n", (fFullClearIsFree ? "YES" : "NO"));
     r.appendf("Drops tile on zero divide: %s\n", (fDropsTileOnZeroDivide ? "YES" : "NO"));
     return r;
 }