101 lines
4.5 KiB
Diff
101 lines
4.5 KiB
Diff
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From f25787b72c20e97cdeb74e037dc1ff56a88b45c6 Mon Sep 17 00:00:00 2001
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From: Ben Wagner <bungeman@google.com>
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Date: Tue, 1 Dec 2020 20:22:00 -0500
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Subject: [PATCH] Subpixel anti-aliasing in FreeType 2.8.1+
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FreeType 2.8.1 and later always provide some form of subpixel
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anti-aliasing.
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Bug: skia:10950,skia:6663
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Change-Id: I666cc942e73b73073cdabf900c25faa10d9aaf0f
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Reviewed-on: https://skia-review.googlesource.com/c/skia/+/339861
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Reviewed-by: Herb Derby <herb@google.com>
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Commit-Queue: Ben Wagner <bungeman@google.com>
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---
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src/ports/SkFontHost_FreeType.cpp | 33 ++++++++++++++++++++-----------
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1 file changed, 22 insertions(+), 11 deletions(-)
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diff --git a/src/ports/SkFontHost_FreeType.cpp b/src/ports/SkFontHost_FreeType.cpp
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index 990eff4f5e..c0aeb792da 100644
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--- a/src/ports/SkFontHost_FreeType.cpp
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+++ b/src/ports/SkFontHost_FreeType.cpp
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@@ -32,6 +32,7 @@
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#include "src/utils/SkMatrix22.h"
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#include <memory>
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+#include <tuple>
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#include <ft2build.h>
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#include FT_ADVANCES_H
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@@ -147,13 +148,16 @@ public:
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// *reinterpret_cast<void**>(&procPtr) = dlsym(self, "proc");
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// because clang has not implemented DR573. See http://clang.llvm.org/cxx_dr_status.html .
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- FT_Int major, minor, patch;
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- FT_Library_Version(fLibrary, &major, &minor, &patch);
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+ using Version = std::tuple<FT_Int, FT_Int, FT_Int>;
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+ Version version;
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+ FT_Library_Version(fLibrary, &std::get<0>(version),
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+ &std::get<1>(version),
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+ &std::get<2>(version));
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#if SK_FREETYPE_MINIMUM_RUNTIME_VERSION >= 0x02070100
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fGetVarDesignCoordinates = FT_Get_Var_Design_Coordinates;
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#elif SK_FREETYPE_MINIMUM_RUNTIME_VERSION & SK_FREETYPE_DLOPEN
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- if (major > 2 || ((major == 2 && minor > 7) || (major == 2 && minor == 7 && patch >= 0))) {
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+ if (Version(2,7,0) <= version) {
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//The FreeType library is already loaded, so symbols are available in process.
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void* self = dlopen(nullptr, RTLD_LAZY);
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if (self) {
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@@ -166,7 +170,7 @@ public:
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#if SK_FREETYPE_MINIMUM_RUNTIME_VERSION >= 0x02070200
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FT_Set_Default_Properties(fLibrary);
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#elif SK_FREETYPE_MINIMUM_RUNTIME_VERSION & SK_FREETYPE_DLOPEN
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- if (major > 2 || ((major == 2 && minor > 7) || (major == 2 && minor == 7 && patch >= 1))) {
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+ if (Version(2,7,1) <= version) {
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//The FreeType library is already loaded, so symbols are available in process.
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void* self = dlopen(nullptr, RTLD_LAZY);
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if (self) {
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@@ -185,7 +189,7 @@ public:
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#if SK_FREETYPE_MINIMUM_RUNTIME_VERSION >= 0x02080000
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fLightHintingIsYOnly = true;
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#else
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- if (major > 2 || ((major == 2 && minor > 8) || (major == 2 && minor == 8 && patch >= 0))) {
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+ if (Version(2,8,0) <= version) {
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fLightHintingIsYOnly = true;
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}
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#endif
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@@ -194,7 +198,7 @@ public:
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#if SK_FREETYPE_MINIMUM_RUNTIME_VERSION >= 0x02080100
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fGetVarAxisFlags = FT_Get_Var_Axis_Flags;
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#elif SK_FREETYPE_MINIMUM_RUNTIME_VERSION & SK_FREETYPE_DLOPEN
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- if (major > 2 || ((major == 2 && minor > 7) || (major == 2 && minor == 7 && patch >= 0))) {
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+ if (Version(2,7,0) <= version) {
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//The FreeType library is already loaded, so symbols are available in process.
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void* self = dlopen(nullptr, RTLD_LAZY);
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if (self) {
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@@ -204,11 +208,18 @@ public:
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}
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#endif
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- // Setup LCD filtering. This reduces color fringes for LCD smoothed glyphs.
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- // The default has changed over time, so this doesn't mean the same thing to all users.
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- if (FT_Library_SetLcdFilter(fLibrary, FT_LCD_FILTER_DEFAULT) == 0) {
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- fIsLCDSupported = true;
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- fLCDExtra = 2; //Using a filter adds one full pixel to each side.
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+ fIsLCDSupported =
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+ // Subpixel anti-aliasing may be unfiltered until the LCD filter is set.
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+ // Newer versions may still need this, so this test with side effects must come first.
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+ // The default has changed over time, so this doesn't mean the same thing to all users.
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+ (FT_Library_SetLcdFilter(fLibrary, FT_LCD_FILTER_DEFAULT) == 0) ||
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+
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+ // In 2.8.1 and later FreeType always provides some form of subpixel anti-aliasing.
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+ ((SK_FREETYPE_MINIMUM_RUNTIME_VERSION) >= 0x02080100) ||
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+ (Version(2,8,1) <= version);
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+
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+ if (fIsLCDSupported) {
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+ fLCDExtra = 2; // Using a filter may require up to one full pixel to each side.
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}
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}
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~FreeTypeLibrary() {
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