diff --git a/en/application-dev/napi/Readme-EN.md b/en/application-dev/napi/Readme-EN.md index ebcb811f7886a097c741198f0696b61327cefefb..9ab337ed1c29e18772ff4e348c47e3202f74815f 100644 --- a/en/application-dev/napi/Readme-EN.md +++ b/en/application-dev/napi/Readme-EN.md @@ -1,6 +1,6 @@ # Native APIs - [Using Native APIs in Application Projects](napi-guidelines.md) - +- [Drawing Development](drawing-guidelines.md) - [Raw File Development](rawfile-guidelines.md) diff --git a/en/application-dev/napi/drawing-guidelines.md b/en/application-dev/napi/drawing-guidelines.md new file mode 100644 index 0000000000000000000000000000000000000000..e813f84d92d4155e78c9ca651af6a3e3cd010232 --- /dev/null +++ b/en/application-dev/napi/drawing-guidelines.md @@ -0,0 +1,208 @@ +# Drawing Development + +## When to Use + +The Native Drawing module provides APIs for drawing 2D graphics and text. The following scenarios are common for drawing development: +* Drawing 2D graphics +* Drawing and painting text + +## Available APIs + +| API| Description| +| -------- | -------- | +| OH_Drawing_BitmapCreate (void) | Creates a bitmap object.| +| OH_Drawing_BitmapBuild (OH_Drawing_Bitmap *, const uint32_t width, const uint32_t height, const OH_Drawing_BitmapFormat *) | Initializes the width and height of a bitmap object and sets the pixel format for the bitmap.| +| OH_Drawing_CanvasCreate (void) | Creates a canvas object.| +| OH_Drawing_CanvasBind (OH_Drawing_Canvas *, OH_Drawing_Bitmap *) | Binds a bitmap to a canvas so that the content drawn on the canvas is output to the bitmap (this process is called CPU rendering).| +| OH_Drawing_CanvasAttachBrush (OH_Drawing_Canvas *, const OH_Drawing_Brush *) | Attaches a brush to a canvas so that the canvas will use the style and color of the brush to fill in a shape.| +| OH_Drawing_CanvasAttachPen (OH_Drawing_Canvas *, const OH_Drawing_Pen *) | Attaches a pen to a canvas so that the canvas will use the style and color of the pen to outline a shape.| +| OH_Drawing_CanvasDrawPath (OH_Drawing_Canvas *, const OH_Drawing_Path *) | Draws a path.| +| OH_Drawing_PathCreate (void) | Creates a path object.| +| OH_Drawing_PathMoveTo (OH_Drawing_Path *, float x, float y) | Sets the start point of a path.| +| OH_Drawing_PathLineTo (OH_Drawing_Path *, float x, float y) | Draws a line segment from the last point of a path to the target point. | +| OH_Drawing_PathClose (OH_Drawing_Path *) | Closes a path. A line segment from the start point to the last point of the path is added.| +| OH_Drawing_PenCreate (void) | Creates a pen object.| +| OH_Drawing_PenSetAntiAlias (OH_Drawing_Pen *, bool) | Checks whether anti-aliasing is enabled for a pen. If anti-aliasing is enabled, edges will be drawn with partial transparency.| +| OH_Drawing_PenSetWidth (OH_Drawing_Pen *, float width) | Sets the thickness for a pen. This thickness determines the width of the outline of a shape.| +| OH_Drawing_BrushCreate (void) | Creates a brush object.| +| OH_Drawing_BrushSetColor (OH_Drawing_Brush *, uint32_t color) | Sets the color for a brush. The color will be used by the brush to fill in a shape.| +| OH_Drawing_CreateTypographyStyle (void) | Creates a `TypographyStyle` object.| +| OH_Drawing_CreateTextStyle (void) | Creates a `TextStyle` object.| +| OH_Drawing_TypographyHandlerAddText (OH_Drawing_TypographyCreate *, const char *) | Sets the text content.| +| OH_Drawing_TypographyPaint (OH_Drawing_Typography *, OH_Drawing_Canvas *, double, double) | Paints text on the canvas.| + + + +## Development Procedure for 2D Graphics Drawing + +The following steps describe how to use the canvas and brush of the Native Drawing module to draw a 2D graphics. + +1. **Create a bitmap object.** Use `OH_Drawing_BitmapCreate` in `drawing_bitmap.h` to create a bitmap object (named `cBitmap` in this example), and use `OH_Drawing_BitmapBuild` to specify its length, width, and pixel format. + + ```c++ + // Create a bitmap object. + OH_Drawing_Bitmap* cBitmap = OH_Drawing_BitmapCreate(); + // Define the pixel format of the bitmap. + OH_Drawing_BitmapFormat cFormat {COLOR_FORMAT_RGBA_8888, ALPHA_FORMAT_OPAQUYE}; + // Set the pixel format for the bitmap. + OH_Drawing_BitmapBuild(cBitmap, width, height, &cFormat); + ``` + +2. **Create a canvas object.** Use `OH_Drawing_CanvasCreate` in `drawing_canvas.h` to create a canvas object (named `cCanvas` in this example), and use `OH_Drawing_CanvasBind` to bind `cBitmap` to this canvas. The content drawn on the canvas will be output to the bound `cBitmap` object. + + ```c++ + // Create a canvas object. + OH_Drawing_Canvas* cCanvas = OH_Drawing_CanvasCreate(); + // Bind the bitmap to the canvas. The content drawn on the canvas will be output to the bound bitmap memory. + OH_Drawing_CanvasBind(cCanvas, cBitmap); + // Use white to clear the canvas. + OH_Drawing_CanvasClear(cCanvas, OH_Drawing_ColorSetArgb(0xFF, 0xFF, 0xFF, 0xFF)); + ``` + +3. **Construct a shape.** Use the APIs provided in `drawing_path.h` to draw a pentagram `cPath`. + + ```c++ + 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; + + // Create a path object and use the APIs to draw a pentagram. + OH_Drawing_Path* cPath = OH_Drawing_PathCreate(); + // Specify the start point of the path. + OH_Drawing_PathMoveTo(cPath, aX, aY); + // Draw a line segment from the last point of a path to the target point. + OH_Drawing_PathLineTo(cPath, bX, bY); + OH_Drawing_PathLineTo(cPath, cX, cY); + OH_Drawing_PathLineTo(cPath, dX, dY); + OH_Drawing_PathLineTo(cPath, eX, eY); + // Close the path. Now the path is drawn. + OH_Drawing_PathClose(cPath); + ``` + +4. **Set the brush and pen styles.** Use `OH_Drawing_PenCreate` in `drawing_pen.h` to create a pen (named `cPen` in this example), and set the attributes such as the anti-aliasing, color, and thickness. The pen is used to outline a shape. Use `OH_Drawing_BrushCreate` in `drawing_brush.h` to create a brush (named `cBrush` in this example), and set the brush color. The brush is used to fill in a shape. Use `OH_Drawing_CanvasAttachPen` and `OH_Drawing_CanvasAttachBrush` in `drawing_canvas.h` to attach the pen and brush to the canvas. + + ```c++ + // Create a pen object and set the anti-aliasing, color, and thickness. + 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); + // Attach the pen to the canvas. + OH_Drawing_CanvasAttachPen(cCanvas, cPen); + + // Create a brush object and set the color. + OH_Drawing_Brush* cBrush = OH_Drawing_BrushCreate(); + OH_Drawing_BrushSetColor(cBrush, OH_Drawing_ColorSetArgb(0xFF, 0x00, 0xFF, 0x00)); + + // Attach the brush to the canvas. + OH_Drawing_CanvasAttachBrush(cCanvas, cBrush); + ``` + +5. **Draw a shape.** Use `OH_Drawing_CanvasDrawPath` in `drawing_canvas.h` to draw a pentagram on the canvas. Call the corresponding APIs to destroy the objects when they are no longer needed. + + ```c++ + // Draw a pentagram on the canvas. The outline of the pentagram is drawn by the pen, and the color is filled in by the brush. + OH_Drawing_CanvasDrawPath(cCanvas, cPath); + // Destroy the created objects when they are no longer needed. + OH_Drawing_BrushDestory(cBrush); + OH_Drawing_PenDestory(cPen); + OH_Drawing_PathDestory(cPath); + ``` + +6. **Obtain pixel data.** Use `OH_Drawing_BitmapGetPixels` in `drawing_bitmap.h` to obtain the pixel address of the bitmap bound to the canvas. The memory to which the address points contains the pixel data of the drawing on the canvas. + + ```c++ + // Obtain the pixel address after drawing. The memory to which the address points contains the pixel data of the drawing on the canvas. + void* bitmapAddr = OH_Drawing_BitmapGetPixels(cBitmap); + auto ret = memcpy_s(addr, addrSize, bitmapAddr, addrSize); + if (ret != EOK) { + LOGI("memcpy_s failed"); + } + // Destroy the canvas object. + OH_Drawing_CanvasDestory(cCanvas); + // Destroy the bitmap object. + OH_Drawing_BitmapDestory(cBitmap); + ``` + +## Development Procedure for Text Drawing and Display + +The following steps describe how to use the text drawing and display feature of the Native Drawing module. +1. **Create a canvas and a bitmap.** + + ```c++ + // Create a bitmap. + OH_Drawing_Bitmap* cBitmap = OH_Drawing_BitmapCreate(); + OH_Drawing_BitmapFormat cFormat {COLOR_FORMAT_RGBA_8888, ALPHA_FORMAT_OPAQUE}; + OH_Drawing_BitmapBuild(cBitmap, width, height, &cFormat); + // Create a canvas. + OH_Drawing_Canvas* cCanvas = OH_Drawing_CanvasCreate(); + OH_Drawing_CanvasBind(cCanvas, cBitmap); + OH_Drawing_CanvasClear(cCanvas, OH_Drawing_ColorSetArgb(0xFF, 0xFF, 0xFF, 0xFF)); + ``` + +2. **Set the typography style.** + + ```c++ + // Set the typography attributes such as left to right (LTR) for the text direction and left-aligned for the text alignment mode. + OH_Drawing_TypographyStyle* typoStyle = OH_Drawing_CreateTypographyStyle(); + OH_Drawing_SetTypographyTextDirection(typoStyle, TEXT_DIRECTION_LTR); + OH_Drawing_SetTypographyTextAlign(typoStyle, TEXT_ALIGN_LEFT); + ``` + +3. **Set the text style.** + + ```c++ + // Set the text color, for example, black. + OH_Drawing_TextStyle* txtStyle = OH_Drawing_CreateTextStyle(); + OH_Drawing_SetTextStyleColor(txtStyle, OH_Drawing_ColorSetArgb(0xFF, 0x00, 0x00, 0x00)); + // Set text attributes such as the font size and weight. + double fontSize = 30; + OH_Drawing_SetTextStyleFontSize(txtStyle, fontSize); + OH_Drawing_SetTextStyleFontWeight(txtStyle, FONT_WEIGHT_400); + OH_Drawing_SetTextStyleBaseLine(txtStyle, TEXT_BASELINE_ALPHABETIC); + OH_Drawing_SetTextStyleFontHeight(txtStyle, 1); + // Set the font families. + const char* fontFamilies[] = {"Roboto"}; + OH_Drawing_SetTextStyleFontFamilies(txtStyle, 1, fontFamilies); + OH_Drawing_SetTextStyleFontStyle(txtStyle, FONT_STYLE_NORMAL); + OH_Drawing_SetTextStyleLocale(txtStyle, "en"); + ``` + +4. **Generate the final text display effect.** + + ```c++ + OH_Drawing_TypographyCreate* handler = OH_Drawing_CreateTypographyHandler(typoStyle, + OH_Drawing_CreateFontCollection()); + OH_Drawing_TypographyHandlerPushTextStyle(handler, txtStyle); + // Set the text content. + const char* text = "OpenHarmony\n"; + OH_Drawing_TypographyHandlerAddText(handler, text); + OH_Drawing_TypographyHandlerPopTextStyle(handler); + OH_Drawing_Typography* typography = OH_Drawing_CreateTypography(handler); + // Set the maximum width. + double maxWidth = 800.0; + OH_Drawing_TypographyLayout(typography, maxWidth); + // Set the start position for text display. + double position[2] = {10.0, 15.0}; + OH_Drawing_TypographyPaint(typography, cCanvas, position[0], position[1]); + ``` + +## Samples + +The following samples are provided to help you better understand how to use the Native Drawing module: +* [2D Graphics Drawing Using Native Drawing](https://gitee.com/openharmony/graphic_graphic_2d/blob/master/rosen/samples/2d_graphics/drawing_c_sample.cpp) +* [Text Drawing and Painting Using Native Drawing](https://gitee.com/openharmony/graphic_graphic_2d/blob/master/rosen/samples/text/renderservice/drawing_text_c_sample.cpp)