Break LCD and Bitmap text dependency on hardcoded atlas values

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/846b022f6b469cfde285372f26e0d5c593d122ac

Review URL: https://codereview.chromium.org/1271873002

4 files changed, 65 insertions, 36 deletions

diff --git a/include/core/SkFloatingPoint.h b/include/core/SkFloatingPoint.h
index 7427562323..f7ee816b12 100644
--- a/include/core/SkFloatingPoint.h
+++ b/include/core/SkFloatingPoint.h
@@ -158,4 +158,13 @@ static inline float sk_float_rsqrt(const float x) {
 #endif
 }
 
+// This is the number of significant digits we can print in a string such that when we read that
+// string back we get the floating point number we expect.  The minimum value C requires is 6, but
+// most compilers support 9
+#ifdef FLT_DECIMAL_DIG
+#define SK_FLT_DECIMAL_DIG FLT_DECIMAL_DIG
+#else
+#define SK_FLT_DECIMAL_DIG 9
+#endif
+
 #endif
diff --git a/src/gpu/GrFontAtlasSizes.h b/src/gpu/GrFontAtlasSizes.h
index 8a3091c6c7..8722ca1a60 100644
--- a/src/gpu/GrFontAtlasSizes.h
+++ b/src/gpu/GrFontAtlasSizes.h
@@ -23,15 +23,6 @@
 #define GR_FONT_ATLAS_NUM_PLOTS_X     (GR_FONT_ATLAS_TEXTURE_WIDTH / GR_FONT_ATLAS_PLOT_WIDTH)
 #define GR_FONT_ATLAS_A8_NUM_PLOTS_X  (GR_FONT_ATLAS_A8_TEXTURE_WIDTH / GR_FONT_ATLAS_A8_PLOT_WIDTH)
 #define GR_FONT_ATLAS_NUM_PLOTS_Y     (GR_FONT_ATLAS_TEXTURE_HEIGHT / GR_FONT_ATLAS_PLOT_HEIGHT)
-
-// one over width and height
-#define GR_FONT_ATLAS_RECIP_WIDTH      "0.00390625"//"0.0009765625"
-#define GR_FONT_ATLAS_A8_RECIP_WIDTH   "0.00390625"//"0.00048828125"
-#define GR_FONT_ATLAS_RECIP_HEIGHT     "0.00390625"//"0.00048828125"
-
-// 1/(3*width)
-// only used for distance fields, which are A8
-#define GR_FONT_ATLAS_LCD_DELTA        "0.001302083"//"0.000162760417"
 #else
 #define GR_FONT_ATLAS_TEXTURE_WIDTH    1024
 #define GR_FONT_ATLAS_A8_TEXTURE_WIDTH 2048
@@ -44,14 +35,5 @@
 #define GR_FONT_ATLAS_NUM_PLOTS_X     (GR_FONT_ATLAS_TEXTURE_WIDTH / GR_FONT_ATLAS_PLOT_WIDTH)
 #define GR_FONT_ATLAS_A8_NUM_PLOTS_X  (GR_FONT_ATLAS_A8_TEXTURE_WIDTH / GR_FONT_ATLAS_A8_PLOT_WIDTH)
 #define GR_FONT_ATLAS_NUM_PLOTS_Y     (GR_FONT_ATLAS_TEXTURE_HEIGHT / GR_FONT_ATLAS_PLOT_HEIGHT)
-
-// one over width and height
-#define GR_FONT_ATLAS_RECIP_WIDTH      "0.0009765625"
-#define GR_FONT_ATLAS_A8_RECIP_WIDTH   "0.00048828125"
-#define GR_FONT_ATLAS_RECIP_HEIGHT     "0.00048828125"
-
-// 1/(3*width)
-// only used for distance fields, which are A8
-#define GR_FONT_ATLAS_LCD_DELTA        "0.000162760417"
 #endif
 #endif
diff --git a/src/gpu/effects/GrBitmapTextGeoProc.cpp b/src/gpu/effects/GrBitmapTextGeoProc.cpp
index a0350e99f5..9496dbffc3 100644
--- a/src/gpu/effects/GrBitmapTextGeoProc.cpp
+++ b/src/gpu/effects/GrBitmapTextGeoProc.cpp
@@ -28,18 +28,19 @@ public:
         // emit attributes
         vsBuilder->emitAttributes(cte);
 
+        // compute numbers to be hardcoded to convert texture coordinates from int to float
+        SkASSERT(cte.numTextures() == 1);
+        GrTexture* atlas = cte.textureAccess(0).getTexture();
+        SkASSERT(atlas);
+        SkScalar recipWidth = 1.0f / atlas->width();
+        SkScalar recipHeight = 1.0f / atlas->height();
+
         GrGLVertToFrag v(kVec2f_GrSLType);
         pb->addVarying("TextureCoords", &v);
-        // this is only used with text, so our texture bounds always match the glyph atlas
-        if (cte.maskFormat() == kA8_GrMaskFormat) {
-            vsBuilder->codeAppendf("%s = vec2(" GR_FONT_ATLAS_A8_RECIP_WIDTH ", "
-                                   GR_FONT_ATLAS_RECIP_HEIGHT ")*%s;", v.vsOut(),
-                                   cte.inTextureCoords()->fName);
-        } else {
-            vsBuilder->codeAppendf("%s = vec2(" GR_FONT_ATLAS_RECIP_WIDTH ", "
-                                   GR_FONT_ATLAS_RECIP_HEIGHT ")*%s;", v.vsOut(),
-                                   cte.inTextureCoords()->fName);
-        }
+        vsBuilder->codeAppendf("%s = vec2(%.*f, %.*f) * %s;", v.vsOut(),
+                               SK_FLT_DECIMAL_DIG, recipWidth,
+                               SK_FLT_DECIMAL_DIG, recipHeight,
+                               cte.inTextureCoords()->fName);
 
         // Setup pass through color
         if (!cte.colorIgnored()) {
@@ -102,6 +103,13 @@ public:
         key |= gp.colorIgnored() ? 0x2 : 0x0;
         key |= gp.maskFormat() << 3;
         b->add32(key);
+
+        // Currently we hardcode numbers to convert atlas coordinates to normalized floating point
+        SkASSERT(gp.numTextures() == 1);
+        GrTexture* atlas = gp.textureAccess(0).getTexture();
+        SkASSERT(atlas);
+        b->add32(atlas->width());
+        b->add32(atlas->height());
     }
 
 private:
diff --git a/src/gpu/effects/GrDistanceFieldGeoProc.cpp b/src/gpu/effects/GrDistanceFieldGeoProc.cpp
index 8af5631cc5..0b97bb2b94 100755
--- a/src/gpu/effects/GrDistanceFieldGeoProc.cpp
+++ b/src/gpu/effects/GrDistanceFieldGeoProc.cpp
@@ -77,11 +77,18 @@ public:
         args.fPB->addVarying("IntTextureCoords", &st, kHigh_GrSLPrecision);
         vsBuilder->codeAppendf("%s = %s;", st.vsOut(), dfTexEffect.inTextureCoords()->fName);
 
+        // compute numbers to be hardcoded to convert texture coordinates from int to float
+        SkASSERT(dfTexEffect.numTextures() == 1);
+        GrTexture* atlas = dfTexEffect.textureAccess(0).getTexture();
+        SkASSERT(atlas);
+        SkScalar recipWidth = 1.0f / atlas->width();
+        SkScalar recipHeight = 1.0f / atlas->height();
+
         GrGLVertToFrag uv(kVec2f_GrSLType);
         args.fPB->addVarying("TextureCoords", &uv, kHigh_GrSLPrecision);
-        // this is only used with text, so our texture bounds always match the glyph atlas
-        vsBuilder->codeAppendf("%s = vec2(" GR_FONT_ATLAS_A8_RECIP_WIDTH ", "
-                               GR_FONT_ATLAS_RECIP_HEIGHT ")*%s;", uv.vsOut(),
+        vsBuilder->codeAppendf("%s = vec2(%.*f, %.*f) * %s;", uv.vsOut(),
+                               SK_FLT_DECIMAL_DIG, recipWidth,
+                               SK_FLT_DECIMAL_DIG, recipHeight,
                                dfTexEffect.inTextureCoords()->fName);
         
         // Use highp to work around aliasing issues
@@ -176,6 +183,13 @@ public:
         key |= dfTexEffect.colorIgnored() << 17;
         key |= ComputePosKey(dfTexEffect.viewMatrix()) << 25;
         b->add32(key);
+
+        // Currently we hardcode numbers to convert atlas coordinates to normalized floating point
+        SkASSERT(gp.numTextures() == 1);
+        GrTexture* atlas = gp.textureAccess(0).getTexture();
+        SkASSERT(atlas);
+        b->add32(atlas->width());
+        b->add32(atlas->height());
     }
 
 private:
@@ -525,11 +539,18 @@ public:
         args.fPB->addVarying("IntTextureCoords", &st, kHigh_GrSLPrecision);
         vsBuilder->codeAppendf("%s = %s;", st.vsOut(), dfTexEffect.inTextureCoords()->fName);
 
+        // compute numbers to be hardcoded to convert texture coordinates from int to float
+        SkASSERT(dfTexEffect.numTextures() == 1);
+        GrTexture* atlas = dfTexEffect.textureAccess(0).getTexture();
+        SkASSERT(atlas);
+        SkScalar recipWidth = 1.0f / atlas->width();
+        SkScalar recipHeight = 1.0f / atlas->height();
+
         GrGLVertToFrag uv(kVec2f_GrSLType);
         args.fPB->addVarying("TextureCoords", &uv, kHigh_GrSLPrecision);
-        // this is only used with text, so our texture bounds always match the glyph atlas
-        vsBuilder->codeAppendf("%s = vec2(" GR_FONT_ATLAS_A8_RECIP_WIDTH ", "
-                               GR_FONT_ATLAS_RECIP_HEIGHT ")*%s;", uv.vsOut(),
+        vsBuilder->codeAppendf("%s = vec2(%.*f, %.*f) * %s;", uv.vsOut(),
+                               SK_FLT_DECIMAL_DIG, recipWidth,
+                               SK_FLT_DECIMAL_DIG, recipHeight,
                                dfTexEffect.inTextureCoords()->fName);
 
         // add frag shader code
@@ -545,10 +566,12 @@ public:
         fsBuilder->codeAppendf("vec2 uv = %s;\n", uv.fsIn());
         fsBuilder->codeAppend(GrGLShaderVar::PrecisionString(kHigh_GrSLPrecision,
                                                              pb->ctxInfo().standard()));
+
+        SkScalar lcdDelta = 1.0f / (3.0f * atlas->width());
         if (dfTexEffect.getFlags() & kBGR_DistanceFieldEffectFlag) {
-            fsBuilder->codeAppend("float delta = -" GR_FONT_ATLAS_LCD_DELTA ";\n");
+            fsBuilder->codeAppendf("float delta = -%.*f;\n", SK_FLT_DECIMAL_DIG, lcdDelta);
         } else {
-            fsBuilder->codeAppend("float delta = " GR_FONT_ATLAS_LCD_DELTA ";\n");
+            fsBuilder->codeAppendf("float delta = %.*f;\n", SK_FLT_DECIMAL_DIG, lcdDelta);
         }
         if (isUniformScale) {
             fsBuilder->codeAppendf("float dy = abs(dFdy(%s.y));", st.fsIn());
@@ -668,6 +691,13 @@ public:
         key |= dfTexEffect.colorIgnored() << 16;
         key |= ComputePosKey(dfTexEffect.viewMatrix()) << 25;
         b->add32(key);
+
+        // Currently we hardcode numbers to convert atlas coordinates to normalized floating point
+        SkASSERT(gp.numTextures() == 1);
+        GrTexture* atlas = gp.textureAccess(0).getTexture();
+        SkASSERT(atlas);
+        b->add32(atlas->width());
+        b->add32(atlas->height());
     }
 
 private: