借鉴的文章:
Skia深入分析5——skia文字绘制的实现
Android's Font Renderer Efficient text rendering with OpenGL ES
万万没想到——flutter这样外接纹理
Text Rendering
flutter/engine/third_party/txt/src
hwui/FontRenderer.cpp
hwui/pipeline/skia/LayerDrawable
FreeTypeLibAndroidJNIDemo
Skia实现的Lottie播放器
libgdx/wiki/Bitmap-fonts
snada/BitmapFontLoader
aosp/libs/hwui/FontRenderer.cpp
https://github.com/libgdx/libgdx/issues/5825
使用CMake交叉编译Skia(下载Demo后,仍需按照文章完成编译)
-矢量文字SDF
libgdx/wiki/Distance-field-fonts
Playing around with distance field font rendering
multi-channel distance field
最后还是选择各个平台的原生API画,比如安卓用的是Canvas DrawText的API:
然后绘制文字参考了以下文章:
HenCoder Android 开发进阶:自定义 View 1-3 文字的绘制
HenCoder Android 开发进阶: 自定义 View 1-2 Paint 详解
文字测量:
Android: Measure Text Height on a Canvas
Measuring text height to be drawn on Canvas ( Android )
查看字体工具 FontLab 7
Android TextView的换行策略
Android换行调试tip:
Painter.measureText()打印的字宽和字号不是完全成正比(即使是画单个字符也不会成正比),比如0.6555倍的字号, kerning为0Painter.measureText()的值会是0.650倍。这样就会导致换行在某些情况下有差异: 文本框2440.6555 = 160; 字号 218.42773 0.6555 = 143.2 字宽246*0.654 = 160; 所以之前换行的转换后不换行了
Painter的textSize设置为142/143/144, measureText("FF")的值都是160.0。设置为148后未166.0,有时候小数位有值,即变化非线性。所以建议在APP层把文字换行,用增加了换行符后的文本替换本来的文本。
-基于FreeType的文字引擎渲染多语言文本:
- 可以监听输入法的locale, 然后自行确认locale对应的ttf:
Get keyboard language or detect user input language in Android
- 也可以参考skia, 将文本转换成unicode后,选择对应的ttf:
a. Android: Find out which font file is appropriate for the characters I want to display
b. SkShaper.cpp里的 void consume() override 方法
- 字体的选择:
Since the Ice Cream Sandwich release, Roboto has been the standard typeface on Android. Since Froyo, Noto has been the standard typeface on Android for all languages not covered by Roboto. Noto is also the standard typeface for all languages on Chrome OS.
Noto开源免费,所以可以选择Noto作为字体文件库