1 /*
2 * Copyright (C) 2023 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <SkFontMetrics.h>
18 #include <SkRRect.h>
19 #include <SkTextBlob.h>
20
21 #include "../utils/Color.h"
22 #include "Canvas.h"
23 #include "FeatureFlags.h"
24 #include "MinikinUtils.h"
25 #include "Paint.h"
26 #include "Properties.h"
27 #include "RenderNode.h"
28 #include "Typeface.h"
29 #include "hwui/PaintFilter.h"
30 #include "pipeline/skia/SkiaRecordingCanvas.h"
31
32 #ifdef __ANDROID__
33 #include <com_android_graphics_hwui_flags.h>
34 namespace flags = com::android::graphics::hwui::flags;
35 #else
36 namespace flags {
high_contrast_text_luminance()37 constexpr bool high_contrast_text_luminance() {
38 return false;
39 }
high_contrast_text_small_text_rect()40 constexpr bool high_contrast_text_small_text_rect() {
41 return false;
42 }
43 } // namespace flags
44 #endif
45
46 namespace android {
47
48 // These should match the constants in framework/base/core/java/android/text/Layout.java
49 inline constexpr float kHighContrastTextBorderWidth = 4.0f;
50 inline constexpr float kHighContrastTextBorderWidthFactor = 0.2f;
51
drawStroke(SkScalar left,SkScalar right,SkScalar top,SkScalar thickness,const Paint & paint,Canvas * canvas)52 static inline void drawStroke(SkScalar left, SkScalar right, SkScalar top, SkScalar thickness,
53 const Paint& paint, Canvas* canvas) {
54 const SkScalar strokeWidth = fmax(thickness, 1.0f);
55 const SkScalar bottom = top + strokeWidth;
56 canvas->drawRect(left, top, right, bottom, paint);
57 }
58
simplifyPaint(int color,Paint * paint)59 static void simplifyPaint(int color, Paint* paint) {
60 paint->setColor(color);
61 paint->setShader(nullptr);
62 paint->setColorFilter(nullptr);
63 paint->setLooper(nullptr);
64
65 if (flags::high_contrast_text_small_text_rect()) {
66 paint->setStrokeWidth(
67 std::max(kHighContrastTextBorderWidth,
68 kHighContrastTextBorderWidthFactor * paint->getSkFont().getSize()));
69 } else {
70 auto borderWidthFactor = 0.04f;
71 paint->setStrokeWidth(kHighContrastTextBorderWidth +
72 borderWidthFactor * paint->getSkFont().getSize());
73 }
74 paint->setStrokeJoin(SkPaint::kRound_Join);
75 paint->setLooper(nullptr);
76 paint->setBlendMode(SkBlendMode::kSrcOver);
77 }
78
79 class DrawTextFunctor {
80 public:
81 /**
82 * Creates a Functor to draw the given text layout.
83 *
84 * @param layout
85 * @param canvas
86 * @param paint
87 * @param x
88 * @param y
89 * @param totalAdvance
90 * @param bounds bounds of the text. Only required if high contrast text mode is enabled.
91 */
DrawTextFunctor(const minikin::Layout & layout,Canvas * canvas,const Paint & paint,float x,float y,float totalAdvance)92 DrawTextFunctor(const minikin::Layout& layout, Canvas* canvas, const Paint& paint, float x,
93 float y, float totalAdvance)
94 : layout(layout)
95 , canvas(canvas)
96 , paint(paint)
97 , x(x)
98 , y(y)
99 , totalAdvance(totalAdvance)
100 , underlinePosition(0)
101 , underlineThickness(0) {}
102
operator()103 void operator()(size_t start, size_t end) {
104 auto glyphFunc = [&](uint16_t* text, float* positions) {
105 for (size_t i = start, textIndex = 0, posIndex = 0; i < end; i++) {
106 text[textIndex++] = layout.getGlyphId(i);
107 positions[posIndex++] = x + layout.getX(i);
108 positions[posIndex++] = y + layout.getY(i);
109 }
110 };
111
112 size_t glyphCount = end - start;
113
114 if (CC_UNLIKELY(canvas->isHighContrastText() && paint.getAlpha() != 0)) {
115 // high contrast draw path
116 int color = paint.getColor();
117 bool darken;
118 // This equation should match the one in core/java/android/text/Layout.java
119 if (flags::high_contrast_text_luminance()) {
120 uirenderer::Lab lab = uirenderer::sRGBToLab(color);
121 darken = lab.L <= 50;
122 } else {
123 int channelSum = SkColorGetR(color) + SkColorGetG(color) + SkColorGetB(color);
124 darken = channelSum < (128 * 3);
125 }
126
127 // outline
128 gDrawTextBlobMode = DrawTextBlobMode::HctOutline;
129 Paint outlinePaint(paint);
130 simplifyPaint(darken ? SK_ColorWHITE : SK_ColorBLACK, &outlinePaint);
131 outlinePaint.setStyle(SkPaint::kStrokeAndFill_Style);
132 canvas->drawGlyphs(glyphFunc, glyphCount, outlinePaint, x, y, totalAdvance);
133
134 // inner
135 gDrawTextBlobMode = DrawTextBlobMode::HctInner;
136 Paint innerPaint(paint);
137 simplifyPaint(darken ? SK_ColorBLACK : SK_ColorWHITE, &innerPaint);
138 innerPaint.setStyle(SkPaint::kFill_Style);
139 canvas->drawGlyphs(glyphFunc, glyphCount, innerPaint, x, y, totalAdvance);
140 gDrawTextBlobMode = DrawTextBlobMode::Normal;
141 } else {
142 // standard draw path
143 canvas->drawGlyphs(glyphFunc, glyphCount, paint, x, y, totalAdvance);
144 }
145
146 // Extract underline position and thickness.
147 if (paint.isUnderline()) {
148 SkFontMetrics metrics;
149 paint.getSkFont().getMetrics(&metrics);
150 const float textSize = paint.getSkFont().getSize();
151 SkScalar position;
152 if (!metrics.hasUnderlinePosition(&position)) {
153 position = textSize * Paint::kStdUnderline_Top;
154 }
155 SkScalar thickness;
156 if (!metrics.hasUnderlineThickness(&thickness)) {
157 thickness = textSize * Paint::kStdUnderline_Thickness;
158 }
159
160 // If multiple fonts are used, use the most bottom position and most thick stroke
161 // width as the underline position. This follows the CSS standard:
162 // https://www.w3.org/TR/css-text-decor-3/#text-underline-position-property
163 // <quote>
164 // The exact position and thickness of line decorations is UA-defined in this level.
165 // However, for underlines and overlines the UA must use a single thickness and
166 // position on each line for the decorations deriving from a single decorating box.
167 // </quote>
168 underlinePosition = std::max(underlinePosition, position);
169 underlineThickness = std::max(underlineThickness, thickness);
170 }
171 }
172
getUnderlinePosition()173 float getUnderlinePosition() const { return underlinePosition; }
getUnderlineThickness()174 float getUnderlineThickness() const { return underlineThickness; }
175
176 private:
177 const minikin::Layout& layout;
178 Canvas* canvas;
179 const Paint& paint;
180 float x;
181 float y;
182 float totalAdvance;
183 float underlinePosition;
184 float underlineThickness;
185 };
186
187 } // namespace android
188