表面视图：文本在不同的图层上绘制

Question

目标：逐字绘制文字

结果：文字绘制在不同的图层上： 要绘制的文字：Hello World !!!

1. 
2. 

公共类DrawThread扩展Thread {     public static final String TAG = DrawThread.class.getSimpleName（）;

private SurfaceHolder surfaceHolder;
private String word;
private Paint paint;

public DrawThread(SurfaceHolder surfaceHolder, String word, Paint paint){
    this.surfaceHolder = surfaceHolder;
    this.word = word;
    this.paint = paint;
}

@Override
public void run() {
    String letterToDraw;
    int wordLength = word.length();
    int counter = 0;
    while (counter < wordLength){

        Canvas canvas = surfaceHolder.lockCanvas(null);

            letterToDraw = word.charAt(counter)+"";
            canvas.drawText(letterToDraw, 20 + counter*20, 40, paint);

        surfaceHolder.unlockCanvasAndPost(canvas);
        counter++;
        try {
            sleep(500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

}

}

public class MySurfaceView扩展了SurfaceView {     private Paint paint = new Paint（Paint.ANTI_ALIAS_FLAG）;

public MySurfaceView(Context context) {
    super(context);

    init();
}

public MySurfaceView(Context context, AttributeSet attrs) {
    super(context, attrs);

    init();
}

public MySurfaceView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);

    init();
}

private void init(){
    paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeWidth(1);
    paint.setTextSize(45);
    paint.setColor(Color.CYAN);
}

public void drawText(){
    DrawThread drawThread = new DrawThread(getHolder(), "Hello World!!!", paint);
    drawThread.run();
}

}

Answer 1

问题在于SurfaceView是双缓冲还是三缓冲，并且您不是每次都重绘整个屏幕。因此，替代字母最终会在每个缓冲区中结束。

每次拨打Canvas#lockCanvas()时，都应该清除并重绘整个屏幕。然后创建一个内部循环，用于绘制从0到counter的字母，而不只是counter处的字母。

（你还需要考虑每个字母的宽度，这样它们就不会相互叠加，但这是一个完全不同的东西。）

有关Android图形和SurfaceView行为的一些背景资料here。