Add shader-based text gamma correction
To enable it, the system property ro.hwui.text_gamma_shader must be
set to true. For testing, DEBUG_FONT_RENDERER_FORCE_SHADER_GAMMA
can be set to 1 in libhwui/Debug.h.
Change-Id: If345c6b71b67ecf1ef2e8847b71f30f3ef251a27
diff --git a/libs/hwui/ProgramCache.cpp b/libs/hwui/ProgramCache.cpp
index a7f1277..fc60279 100644
--- a/libs/hwui/ProgramCache.cpp
+++ b/libs/hwui/ProgramCache.cpp
@@ -159,6 +159,9 @@
// PorterDuff
"uniform vec4 colorBlend;\n"
};
+const char* gFS_Uniforms_Gamma =
+ "uniform float gamma;\n";
+
const char* gFS_Main =
"\nvoid main(void) {\n"
" lowp vec4 fragColor;\n";
@@ -184,10 +187,18 @@
"\nvoid main(void) {\n"
" gl_FragColor = texture2D(sampler, outTexCoords);\n"
"}\n\n";
+const char* gFS_Fast_SingleA8Texture_ApplyGamma =
+ "\nvoid main(void) {\n"
+ " gl_FragColor = vec4(0.0, 0.0, 0.0, pow(texture2D(sampler, outTexCoords).a, gamma));\n"
+ "}\n\n";
const char* gFS_Fast_SingleModulateA8Texture =
"\nvoid main(void) {\n"
" gl_FragColor = color * texture2D(sampler, outTexCoords).a;\n"
"}\n\n";
+const char* gFS_Fast_SingleModulateA8Texture_ApplyGamma =
+ "\nvoid main(void) {\n"
+ " gl_FragColor = color * pow(texture2D(sampler, outTexCoords).a, gamma);\n"
+ "}\n\n";
const char* gFS_Fast_SingleGradient =
"\nvoid main(void) {\n"
" gl_FragColor = texture2D(gradientSampler, linear);\n"
@@ -202,6 +213,8 @@
" fragColor = color;\n";
const char* gFS_Main_ModulateColor =
" fragColor *= color.a;\n";
+const char* gFS_Main_ModulateColor_ApplyGamma =
+ " fragColor *= pow(color.a, gamma);\n";
const char* gFS_Main_AccountForAA =
" if (widthProportion < boundaryWidth) {\n"
" fragColor *= (widthProportion * inverseBoundaryWidth);\n"
@@ -517,6 +530,9 @@
if (description.hasBitmap && description.isPoint) {
shader.append(gFS_Header_Uniforms_PointHasBitmap);
}
+ if (description.hasGammaCorrection) {
+ shader.append(gFS_Uniforms_Gamma);
+ }
// Optimization for common cases
if (!description.isAA && !blendFramebuffer &&
@@ -544,9 +560,17 @@
fast = true;
} else if (singleA8Texture) {
if (!description.modulate) {
- shader.append(gFS_Fast_SingleA8Texture);
+ if (description.hasGammaCorrection) {
+ shader.append(gFS_Fast_SingleA8Texture_ApplyGamma);
+ } else {
+ shader.append(gFS_Fast_SingleA8Texture);
+ }
} else {
- shader.append(gFS_Fast_SingleModulateA8Texture);
+ if (description.hasGammaCorrection) {
+ shader.append(gFS_Fast_SingleModulateA8Texture_ApplyGamma);
+ } else {
+ shader.append(gFS_Fast_SingleModulateA8Texture);
+ }
}
fast = true;
} else if (singleGradient) {
@@ -643,7 +667,11 @@
}
}
if (description.modulate && applyModulate) {
- shader.append(gFS_Main_ModulateColor);
+ if (description.hasGammaCorrection) {
+ shader.append(gFS_Main_ModulateColor_ApplyGamma);
+ } else {
+ shader.append(gFS_Main_ModulateColor);
+ }
}
// Apply the color op if needed
shader.append(gFS_Main_ApplyColorOp[description.colorOp]);