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Android，沿路径移动位图？

发布于 2024-10-07 22:11:34 字数 127 浏览 0 评论 0原文

我想知道是否可以从路径中选择坐标来随着时间的推移绘制位图，例如，我有一张太阳的图像，我想随着时间的推移沿着弧形路径移动它。

有没有什么方法可以定义这样的路径，然后沿着它移动，这样我就不必进行数学计算？

谢谢。

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静若繁花 2024-10-14 22:11:34

是的，可以沿着路径移动图像。我将提供简单的解决方案来展示原理。以下代码将移动和旋转您的图像。如果不需要旋转，请删除 TANGENT_MATRIX_FLAG 标志。

import android.graphics.*;
//somewhere global
int iCurStep = 0;// current step

//don't forget to initialize
Path pathMoveAlong = new Path();
private static Bitmap bmImage = null;

@Override
protected void onDraw(Canvas canvas) {
    Matrix mxTransform = new Matrix();
    PathMeasure pm = new PathMeasure(pathMoveAlong, false);
    float fSegmentLen = pm.getLength() / 20;//20 animation steps

    if (iCurStep <= 20) {
        pm.getMatrix(fSegmentLen * iCurStep, mxTransform,
            PathMeasure.POSITION_MATRIX_FLAG + PathMeasure.TANGENT_MATRIX_FLAG);
        canvas.drawBitmap(bmImage, mxTransform, null);
        iCurStep++;
        invalidate();
    } else {
        iCurStep = 0;
    };
};

Yes, it's possible to move image along path. I will provide simple solution to show the principle. The following code will move and rotate your image. If you don't need rotation remove the TANGENT_MATRIX_FLAG flag.

import android.graphics.*;
//somewhere global
int iCurStep = 0;// current step

//don't forget to initialize
Path pathMoveAlong = new Path();
private static Bitmap bmImage = null;

@Override
protected void onDraw(Canvas canvas) {
    Matrix mxTransform = new Matrix();
    PathMeasure pm = new PathMeasure(pathMoveAlong, false);
    float fSegmentLen = pm.getLength() / 20;//20 animation steps

    if (iCurStep <= 20) {
        pm.getMatrix(fSegmentLen * iCurStep, mxTransform,
            PathMeasure.POSITION_MATRIX_FLAG + PathMeasure.TANGENT_MATRIX_FLAG);
        canvas.drawBitmap(bmImage, mxTransform, null);
        iCurStep++;
        invalidate();
    } else {
        iCurStep = 0;
    };
};

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遗弃Ｍ 2024-10-14 22:11:34

以下是我使用的动画师：

目的：沿路径“路径”移动视图“视图”

v21+：

ValueAnimator pathAnimator = ObjectAnimator.ofFloat(view, "x", "y", path)

v11+：

ValueAnimator pathAnimator = ValueAnimator.ofFloat(0.0f, 1.0f);

pathAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
float[] point = new float[2];

@Override
    public void onAnimationUpdate(ValueAnimator animation) {
        float val = animation.getAnimatedFraction();
        PathMeasure pathMeasure = new PathMeasure(path, true);
        pathMeasure.getPosTan(pathMeasure.getLength() * val, point, null);
        view.setX(point[0]);
        view.setY(point[1]);
    }
});

类似要求： https:// /stackoverflow.com/a/30254715/4344057

Here are the animators I use:

Purpose: Move View "view" along Path "path"

v21+:

ValueAnimator pathAnimator = ObjectAnimator.ofFloat(view, "x", "y", path)

v11+:

ValueAnimator pathAnimator = ValueAnimator.ofFloat(0.0f, 1.0f);

pathAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
float[] point = new float[2];

@Override
    public void onAnimationUpdate(ValueAnimator animation) {
        float val = animation.getAnimatedFraction();
        PathMeasure pathMeasure = new PathMeasure(path, true);
        pathMeasure.getPosTan(pathMeasure.getLength() * val, point, null);
        view.setX(point[0]);
        view.setY(point[1]);
    }
});

Similar requirement to: https://stackoverflow.com/a/30254715/4344057

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一身仙ぐ女味 2024-10-14 22:11:34

我正在考虑一种解决方案：

<前><代码>_
/\

如果您的弧具有这种形状（意味着小于半个圆并且水平放置），那么您可以迭代 x 值，并为此 x 获取路径上的 y。然后将位图移动到该位置。

I'm thinking of one solution:

         _
       /   \

If your arc has this kind of shape (meaning less than half a circle and positioned horizontaly) then you could iterate the x value and for that x get the y that's on the path. Then move your bitmap to that position.

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