XComponent、NativeDrawing实现2D图形绘制

/** 
    * 使用 Native Drawing 提供的API接口绘制 
    */ 
  { 
      // 创建一个bitmap对象 
      OH_Drawing_Bitmap *cBitmap = OH_Drawing_BitmapCreate(); 
      // 定义bitmap的像素格式 
      OH_Drawing_BitmapFormat cFormat{COLOR_FORMAT_RGBA_8888, ALPHA_FORMAT_OPAQUE}; 
      // 构造对应格式的bitmap 
      OH_Drawing_BitmapBuild(cBitmap, width, height, &cFormat); 
      // 创建一个canvas对象 
      OH_Drawing_Canvas *cCanvas = OH_Drawing_CanvasCreate(); 
      // 将画布与bitmap绑定，画布画的内容会输出到绑定的bitmap内存中 
      OH_Drawing_CanvasBind(cCanvas, cBitmap); 
      // 使用白色清除画布内容 
      OH_Drawing_CanvasClear(cCanvas, OH_Drawing_ColorSetArgb(0xFF, 0xFF, 0xFF, 0xFF)); 
    /** 
      * 画2D图形 
      */ 
      int len = 300; 
​ 
      float aX = 500; 
      float aY = 500; 
​ 
      float dX = aX - len * std::sin(18.0f); 
      float dY = aY + len * std::cos(18.0f); 
​ 
      float cX = aX + len * std::sin(18.0f); 
      float cY = dY; 
​ 
      float bX = aX + (len / 2.0); 
      float bY = aY + std::sqrt((cX - dX) * (cX - dX) + (len / 2.0) * (len / 2.0)); 
​ 
      float eX = aX - (len / 2.0); 
      float eY = bY; 
​ 
      // 创建一个path对象，然后使用接口连接成一个五角星形状 
      OH_Drawing_Path *cPath = OH_Drawing_PathCreate(); 
      // 指定path的起始位置 
      OH_Drawing_PathMoveTo(cPath, aX, aY); 
      // 用直线连接到目标点 
      OH_Drawing_PathLineTo(cPath, bX, bY); 
      OH_Drawing_PathLineTo(cPath, cX, cY); 
      OH_Drawing_PathLineTo(cPath, dX, dY); 
      OH_Drawing_PathLineTo(cPath, eX, eY); 
      // 闭合形状，path绘制完毕 
      OH_Drawing_PathClose(cPath); 
      // 创建一个画笔Pen对象，Pen对象用于形状的边框线绘制 
      OH_Drawing_Pen *cPen = OH_Drawing_PenCreate(); 
      OH_Drawing_PenSetAntiAlias(cPen, true); 
      OH_Drawing_PenSetColor(cPen, OH_Drawing_ColorSetArgb(0xFF, 0xFF, 0x00, 0x00)); 
      OH_Drawing_PenSetWidth(cPen, 10.0); 
      OH_Drawing_PenSetJoin(cPen, LINE_ROUND_JOIN); 
      // 将Pen画笔设置到canvas中 
      OH_Drawing_CanvasAttachPen(cCanvas, cPen); 
​ 
      // 创建一个画刷Brush对象，Brush对象用于形状的填充 
      OH_Drawing_Brush *cBrush = OH_Drawing_BrushCreate(); 
      OH_Drawing_BrushSetColor(cBrush, OH_Drawing_ColorSetArgb(0xFF, 0x00, 0xFF, 0x00)); 
​ 
      // 将Brush画刷设置到canvas中 
      OH_Drawing_CanvasAttachBrush(cCanvas, cBrush); 
      // 在画布上画path的形状，五角星的边框样式为pen设置，颜色填充为Brush设置 
      OH_Drawing_CanvasDrawPath(cCanvas, cPath); 
      // 销毁创建的对象 
      OH_Drawing_BrushDestroy(cBrush); 
      OH_Drawing_PenDestroy(cPen); 
      OH_Drawing_PathDestroy(cPath); 
      // 画完后获取像素地址，地址指向的内存包含画布画的像素数据 
      // 
      uint8_t *bitmapAddr = static_cast<uint8_t *>(OH_Drawing_BitmapGetPixels(cBitmap)); 
      std::copy(bitmapAddr, bitmapAddr + (width * height * 4), mappedAddr); 
​ 
      //       void *bitmapAddr = OH_Drawing_BitmapGetPixels(cBitmap); 
      //       std::copy(addr, addr + addrSize, static_cast<uint8_t *>(bitmapAddr)); 
      //       const void *bitmapAddr = OH_Drawing_BitmapGetPixels(cBitmap); 
      //       memcpy(mappedAddr, bitmapAddr, width * height * 4); 
​ 
      // 销毁canvas对象 
      OH_Drawing_CanvasDestroy(cCanvas); 
      // 销毁bitmap对象 
      OH_Drawing_BitmapDestroy(cBitmap); 
      /**/ 
      

// 设置刷新区域，如果Region中的Rect为nullptr,或者rectNumber为0，则认为OHNativeWindowBuffer全部有内容更改。 
  Region region{nullptr, 0}; 
  // 通过OH_NativeWindow_NativeWindowFlushBuffer 提交给消费者使用，例如：显示在屏幕上。 
  OH_NativeWindow_NativeWindowFlushBuffer(nativeWindow, buffer, fenceFd, region); 
  // 取消内存映射munmap 
  // 内存使用完记得去掉内存映射 
  int result = munmap(mappedAddr, bufferHandle->size); 
  if (result == -1) { 
      // munmap failed 
  }