Android實作自定義動畫

Animation提供了幾種動畫效果（漸變 縮放 移動），如果想要實作簡單的3D效果或者是疊加兩種動畫又應該怎麼辦？

Android給我們提供了一個叫protected void applyTransformation(float interpolatedTime, Transformation t)的接口，通過重寫這個函數就可以達到想要的效果。

下面上alpha+translate合并動畫的代碼

public class alpha_transAnimation extends Animation {
    private final float transX;
    private final float transY;
    private final float mCenterX;
    private final float mCenterY;
    private Camera mCamera;

    public alpha_transAnimation(float transX, float transY, float centerX, float centerY) {
        this.transX = transX;
        this.transY = transY;
        mCenterX = centerX;
        mCenterY = centerY;
    }

    @Override
    public void initialize(int width, int height, int parentWidth, int parentHeight) {
        super.initialize(width, height, parentWidth, parentHeight);
        mCamera = new Camera();
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {

        final float centerX = mCenterX;
        final float centerY = mCenterY;
        final Camera camera = mCamera;

        final Matrix matrix = t.getMatrix();
        t.setAlpha(1.0f * interpolatedTime);

        camera.save();
        camera.translate(transX * interpolatedTime, transY * interpolatedTime, 0.0f);
        camera.getMatrix(matrix);
        camera.restore();

        matrix.preTranslate(-centerX, -centerY);
        matrix.postTranslate(centerX, centerY);
    }
}