通过相机和矩阵镜像图像

Question

我想按Fragment上的按钮翻转图像。我创建了一个类，该类扩展了Animation类，以使翻转的动画效果如下所示。

import android.graphics.Camera;
import android.graphics.Matrix;
import android.view.animation.Animation;
import android.view.animation.DecelerateInterpolator;
import android.view.animation.Transformation;

public class FlipAnimation extends Animation {
    private int centerX;
    private int centerY;

    private Camera camera = new Camera();

    @Override
    public void initialize(int width, int height, int parentWidth, int parentHeight) {
        super.initialize(width, height, parentWidth, parentHeight);

        centerX = width / 2;
        centerY = width / 2;

        setDuration(1000);
        setInterpolator(new DecelerateInterpolator());
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        final Matrix matrix = t.getMatrix();

        camera.save();
        camera.rotateY(180 * interpolatedTime);
        camera.getMatrix(matrix);

        // Move to image center before rotation, and move back after rotation.
        matrix.preTranslate(-centerX, -centerY);
        matrix.postTranslate(centerX, centerY);

        camera.restore();
    }
}

当我按下按钮时，按如下所示调用动画

public void flipImage() {
        FlipAnimation flipAnimation = new FlipAnimation();
        flipAnimation.setFillAfter(true);
        imageView.startAnimation(flipAnimation);
    }

当我第一次按下按钮时，图像正确翻转（旋转180度），但是当我再次按下按钮时，图像没有翻转回原始状态。

这就是我想要的：

这是我得到的：

当我再次按下按钮时，旋转从原始状态开始，但是我希望它从第一步的结果开始。

Answer 1

在您的班级中定义一个reverse成员。调用applyTransformation时，只需将reverse切换成相反的方向并施加180度的负旋转即可。  Here are some useful examples.

boolean reverse = false;

@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
    final Matrix matrix = t.getMatrix();

    camera.save();

    // Rotate forward or backward.
    if (reverse) {
        camera.rotateY(180 * (1.0f - interpolatedTime));

    } else {
        camera.rotateY(180 * interpolatedTime);
    }

    camera.getMatrix(matrix);

    // Move to image center before rotation, and move back after rotation.
    matrix.preTranslate(-centerX, -centerY);
    matrix.postTranslate(centerX, centerY);

    // Reverse animation.
    reverse = !reverse;

    camera.restore();
}