commit dcd164c25475885d91303811572ddc71dde91788
author Tyler Freeman <fuego@google.com> Thu Oct 19 22:48:34 2023 +0000
committer Tyler Freeman <fuego@google.com> Wed Jan 03 18:31:08 2024 +0000
tree 0c866045d41c015aea3bd13b2cce8ca0863f1f25
parent 6b061bbd0eb4bda94b4c81f94f4108ad247f6d2f

fix(high contrast text): fix grey text sometimes getting lighter when it should get darker and vice-versa

Use perceptual luminance instead of RGB heuristic to decide to lighten
or darken.

Bug: 186567103
Test: manual
1. adb shell setenforce 0 && adb shell setprop persist.device_config.aconfig_flags.accessibility.com.android.graphics.hwui.flags.high_contrast_text_luminance true && adb shell stop && adb shell start

Change-Id: Ief7ae6c10e1043694ffc10b1d827ebeaada61131

libs/hwui/Android.bp

diff --git a/libs/hwui/Android.bp b/libs/hwui/Android.bp
index 79a7357..9751d63 100644
--- a/libs/hwui/Android.bp
+++ b/libs/hwui/Android.bp
@@ -38,6 +38,7 @@
 
 cc_aconfig_library {
     name: "hwui_flags_cc_lib",
+    host_supported: true,
     aconfig_declarations: "hwui_flags",
 }
 
@@ -117,12 +118,15 @@
         "libbase",
         "libharfbuzz_ng",
         "libminikin",
+        "server_configurable_flags",
     ],
 
     static_libs: [
         "libui-types",
     ],
 
+    whole_static_libs: ["hwui_flags_cc_lib"],
+
     target: {
         android: {
             shared_libs: [
@@ -154,7 +158,6 @@
                 "libstatspull_lazy",
                 "libstatssocket_lazy",
                 "libtonemap",
-                "hwui_flags_cc_lib",
             ],
         },
         host: {

libs/hwui/aconfig/hwui_flags.aconfig

diff --git a/libs/hwui/aconfig/hwui_flags.aconfig b/libs/hwui/aconfig/hwui_flags.aconfig
index ca11975..c156c46 100644
--- a/libs/hwui/aconfig/hwui_flags.aconfig
+++ b/libs/hwui/aconfig/hwui_flags.aconfig
@@ -15,6 +15,13 @@
 }
 
 flag {
+  name: "high_contrast_text_luminance"
+  namespace: "accessibility"
+  description: "Use luminance to determine how to make text more high contrast, instead of RGB heuristic"
+  bug: "186567103"
+}
+
+flag {
   name: "hdr_10bit_plus"
   namespace: "core_graphics"
   description: "Use 10101010 and FP16 formats for HDR-UI when available"

libs/hwui/hwui/DrawTextFunctor.h

diff --git a/libs/hwui/hwui/DrawTextFunctor.h b/libs/hwui/hwui/DrawTextFunctor.h
index 2e6e976..8f99990 100644
--- a/libs/hwui/hwui/DrawTextFunctor.h
+++ b/libs/hwui/hwui/DrawTextFunctor.h
@@ -16,7 +16,9 @@
 
 #include <SkFontMetrics.h>
 #include <SkRRect.h>
+#include <com_android_graphics_hwui_flags.h>
 
+#include "../utils/Color.h"
 #include "Canvas.h"
 #include "FeatureFlags.h"
 #include "MinikinUtils.h"
@@ -27,6 +29,8 @@
 #include "hwui/PaintFilter.h"
 #include "pipeline/skia/SkiaRecordingCanvas.h"
 
+namespace flags = com::android::graphics::hwui::flags;
+
 namespace android {
 
 static inline void drawStroke(SkScalar left, SkScalar right, SkScalar top, SkScalar thickness,
@@ -73,8 +77,14 @@
         if (CC_UNLIKELY(canvas->isHighContrastText() && paint.getAlpha() != 0)) {
             // high contrast draw path
             int color = paint.getColor();
-            int channelSum = SkColorGetR(color) + SkColorGetG(color) + SkColorGetB(color);
-            bool darken = channelSum < (128 * 3);
+            bool darken;
+            if (flags::high_contrast_text_luminance()) {
+                uirenderer::Lab lab = uirenderer::sRGBToLab(color);
+                darken = lab.L <= 50;
+            } else {
+                int channelSum = SkColorGetR(color) + SkColorGetG(color) + SkColorGetB(color);
+                darken = channelSum < (128 * 3);
+            }
 
             // outline
             gDrawTextBlobMode = DrawTextBlobMode::HctOutline;