android - 如何更新 Canvas 绘制文本而不是重绘 Canvas-6ren

android - 如何更新 Canvas 绘制文本而不是重绘 Canvas

转载作者：太空宇宙更新时间：2023-11-03 11:25:07

我现在可以在运动 View 的 Canvas 上绘制文本，问题是当我绘制文本并在同一 Canvas 上进行下一次绘制时，我的绘制文本正在消失，我的意思是屏幕正在重绘，因为我想要无效保留我以前的绘图并在同一 Canvas 上绘制新绘图我要怎么做？

@Override
   protected void onDraw(Canvas canvas) {
    Paint hint = new Paint();
    path = new Path();
    mTextPaths = new ArrayList<Path>();
    Log.v("getting mtextpaths", mTextPaths.toString());

    int m;
    if (strgettile != null) {
        for (m = 0; m < strgettile.length(); m++) {
            System.out.println(strgettile.charAt(m));
            char convertst = strgettile.charAt(m);
            characterToString = Character.toString(convertst);

            // canvas.drawText(characterToString, x, y, hint);
            // canvas.drawText(characterToString, m
            // * width + x, m * height + y, foreground); //its working in
            // cross
            // canvas.drawText(characterToString, x, m * height + y,
            // foreground); //its working for vertical
            // canvas.drawText(characterToString, m
            // * width + x, y, foreground); //its working in horizontal
            // setSelectedTile(tile);
            if (getorientation.equalsIgnoreCase("Horizontal")) {
                canvas.drawText(characterToString, m * width + positionX,
                        positionY, foreground); // for motion event
                hint.setColor(Color.BLACK);
                hint.setTextSize(45);
                foreground.getTextPath(characterToString, 0,
                        characterToString.length(), positionX * 2 / 3,
                        positionY - 4, path);

            } else {
                canvas.drawText(characterToString, positionX, m * height
                        + positionY, foreground);
                hint.setColor(Color.BLACK);
                hint.setTextSize(45);
                foreground.getTextPath(characterToString, 0,
                        characterToString.length(), positionX * 2 / 3,
                        positionY - 4, path);


            }


        }

    }

  public void setSelectedTile(String tile, String strorientations) {
    // TODO Auto-generated method stub
    Log.v("getting string in puzzle view ", tile);
    strgettile = tile;
    getorientation = strorientations;
    mTextPaths.add(path);
    invalidate();


}

最佳答案

每当您调用无效()方法。所以我维护所有的文本和位置在 arraylist 中，并在每次单击 Canvas 时绘制 Canvas 。

这是解决您问题的方法之一。 Canvas 只是一个位图。无论你在上面画什么，它都是永久的。有办法处理它，但大多数实现只是重新绘制整个 Canvas 在每一遍上。

下面是代码 fragment :

public class PuzzleView extends View {
private static final String TAG = "Sudoku";
private float width; // width of one tile
private float height; // height of one tile
private int selX; // X index of selection
private int selY; // Y index of selection
private final Rect selRect = new Rect();
private final Game game;
float positionX = 5;
float positionY = 15;
ArrayList<Kirti> data = new ArrayList<Kirti>();
String strgettile = null;

Paint foreground = new Paint(Paint.ANTI_ALIAS_FLAG);
String getorientation;

String characterToString;
Path path;
List<Path> mTextPaths = new ArrayList<Path>();

public PuzzleView(Context context) {
    super(context);
    this.game = (Game) context;
    setFocusable(true);
    setFocusableInTouchMode(true);
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    width = w / 9f;
    height = h / 9f;
    // getRect(selX, selY, selRect);
    Log.d(TAG, "onSizeChanged: width " + width + ", height " + height);
    super.onSizeChanged(w, h, oldw, oldh);
}

@Override
protected void onDraw(Canvas canvas) {
    // super.onDraw(canvas);
    // canvas.save();
    // canvas.restore();
    // Draw the background...
    Paint background = new Paint();
    background.setColor(getResources().getColor(R.color.puzzle_background));
    canvas.drawRect(0, 0, getWidth(), getHeight(), background);

    // Draw the board...
    // Define colors for the grid lines
    Paint dark = new Paint();
    dark.setColor(getResources().getColor(R.color.puzzle_dark));

    Paint hilite = new Paint();
    hilite.setColor(getResources().getColor(R.color.puzzle_hilite));

    Paint light = new Paint();
    light.setColor(getResources().getColor(R.color.puzzle_light));

    // Draw the minor grid lines
    for (int i = 0; i < 9; i++) {
        canvas.drawLine(0, i * height, getWidth(), i * height, light);
        canvas.drawLine(0, i * height + 1, getWidth(), i * height + 1,
                hilite);
        canvas.drawLine(i * width, 0, i * width, getHeight(), light);
        canvas.drawLine(i * width + 1, 0, i * width + 1, getHeight(),
                hilite);
    }

    // Draw the major grid lines
    for (int i = 0; i < 9; i++) {
        if (i % 3 != 0)
            continue;
        canvas.drawLine(0, i * height, getWidth(), i * height, dark);
        canvas.drawLine(0, i * height + 1, getWidth(), i * height + 1,
                hilite);
        canvas.drawLine(i * width, 0, i * width, getHeight(), dark);
        canvas.drawLine(i * width + 1, 0, i * width + 1, getHeight(),
                hilite);
    }

    Paint hint = new Paint();
    path = new Path();

    int m;
    for (int i = 0; i < data.size(); i++) {
        String strgettile = data.get(i).getSt();

        if (strgettile != null) {
            for (m = 0; m < strgettile.length(); m++) {
                System.out.println(strgettile.charAt(m));
                char convertst = strgettile.charAt(m);
                characterToString = Character.toString(convertst);

                if (data.get(i).getorientation
                        .equalsIgnoreCase("Horizontal")) {

                    canvas.drawText(characterToString, m
                            * data.get(i).getWidth()
                            + data.get(i).getXposition(), data.get(i)
                            .getYposition(), foreground); // for motion
                                                          // event

                    hint.setColor(Color.BLACK);
                    hint.setTextSize(45);

                } else {
                    // mTextPaths.add(strgettile);
                    // for (int i = 0; i < mTextPaths.size(); i++) {

                    canvas.drawText(characterToString, data.get(i)
                            .getXposition(), m * data.get(i).getHeight()
                            + data.get(i).getYposition(), foreground);
                    // }

                    hint.setColor(Color.BLACK);
                    hint.setTextSize(45);

                }

            }
            try {
                if (foreground != null) {
                    foreground.getTextPath(characterToString, 0,
                            characterToString.length(), data.get(i)
                                    .getXposition() * 2 / 3, data.get(i)
                                    .getYposition() - 4, path);
                }

            } catch (Exception e) {

            }

        }
    }

}

@Override
public boolean onTouchEvent(MotionEvent event) {
    if (event.getAction() != MotionEvent.ACTION_DOWN)
        game.showKeypadOrError(selX, selY);
    foreground.setColor(getResources().getColor(R.color.puzzle_foreground));
    foreground.setStyle(Style.FILL);
    foreground.setTextSize(height * 0.75f);
    foreground.setTextScaleX(width / height);
    foreground.setTextAlign(Paint.Align.CENTER);
    FontMetrics fm = foreground.getFontMetrics();
    positionX = (int) event.getX();
    positionY = (int) event.getY() - (fm.ascent + fm.descent) / 2;

    return true;
}

public void setSelectedTile(String tile, String strorientations) {
    // TODO Auto-generated method stub
    Log.v("getting string in puzzle view ", tile);
    if (game.setTileIfValid(selX, selY, tile)) {
        strgettile = tile;
        getorientation = strorientations;
        mTextPaths.add(path);
        data.add(new Kirti(positionX, positionY, strgettile,
                getorientation, width, height));
        invalidate();
        Log.v("getting mtextpaths", mTextPaths.toString());
    }

}}

The model class is:

public class Kirti {
float positionX;
float positionY;
String strgettile;
String getorientation;
float width;
float height;
public Kirti(float positionX, float positionY, String strgettile,
        String getorientation, float width, float height) {
    super();
    this.positionX = positionX;
    this.positionY = positionY;
    this.strgettile = strgettile;
    this.getorientation = getorientation;
    this.width = width;
    this.height = height;
}
public float getPositionX() {
    return positionX;
}
public void setPositionX(float positionX) {
    this.positionX = positionX;
}
public float getPositionY() {
    return positionY;
}
public void setPositionY(float positionY) {
    this.positionY = positionY;
}
public String getStrgettile() {
    return strgettile;
}
public void setStrgettile(String strgettile) {
    this.strgettile = strgettile;
}
public String getGetorientation() {
    return getorientation;
}
public void setGetorientation(String getorientation) {
    this.getorientation = getorientation;
}
public float getWidth() {
    return width;
}
public void setWidth(float width) {
    this.width = width;
}
public float getHeight() {
    return height;
}
public void setHeight(float height) {
    this.height = height;
}}

关于android - 如何更新 Canvas 绘制文本而不是重绘 Canvas ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/27170618/

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android - 如何更新 Canvas 绘制文本而不是重绘 Canvas