Android的位图旋转中心的周围无调整 [英] Android rotate bitmap around center without resizing

问题描述

我挣扎提请围绕其中心旋转的位图，并没有做调整位图的旋转。我画我所有的精灵通过游戏线程的屏幕，所以我在寻找一个解决方案，整合了原来的位图，而不是在画布上。

I'm struggling to draw a rotating bitmap around its center and do the rotating without resizing the bitmap. I'm drawing all my sprites to the screen via a game thread, so I'm looking for a solution that incorporates the original bitmap and not the canvas.

在此先感谢。

这是我的code到目前为止，原来绕其中心位图，但调整它的大小。

This is my code so far, it turns a bitmap around its center, yet resizes it.

i = i + 2;
            transform.postRotate(i, Assets.scoresScreen_LevelStar.getWidth()/2, Assets.scoresScreen_LevelStar.getHeight()/2);
            Bitmap resizedBitmap = Bitmap.createBitmap(Assets.scoresScreen_LevelStar, 0, 0, Assets.scoresScreen_LevelStar.getWidth(), Assets.scoresScreen_LevelStar.getHeight(), transform, true);

            game.getGraphics().getCanvasGameScreen().drawBitmap(resizedBitmap, null, this.levelStar.getHolderPolygons().get(0), null);

更新：

我发现这并不像听起来那么容易。我的旋转code是没有问题的。位图旋转，但DST的矩形也将不得不增加/减少取决于旋转的角度，否则bimap的会出现较小的，因为它绘制成一个固定的DST正确。 所以，我猜我会开发一些方法会返回一个DST正确。 所以方法需要旋转的位图没有出现调整：的

I've noticed this isn't as easy as it sounds. My rotating code is not the problem. The bitmap rotates, yet the dst rect will also have to increase/decrease depending on the angle of rotation, or else the bimap will appear smaller, since it's drawn into a fixed dst rect. So I'm guessing I'll have to develop some method that will return a dst rect. So the methods needed to rotate a bitmap without appeared resizing:

public static Bitmap rotateBitmap(Bitmap bitmap, int rotation) // I've got this method working

和

public static Rect rotateRect(Rect currentDst, int rotation) // Don't got this

据我所知，这将需要一些数学（三角函数），任何人都准备迎接挑战？ ：P

I understand this will require some math (trig), anyone up for the challenge? :P

推荐答案

这为我工作！

我创建了一个返回一个矩阵的方法。基质可以在以下拉伸方法可以使用​​：

I created a method that returns a matrix. The matrix can be used in the following drawing method:

public void drawBitmap (Bitmap bitmap, Matrix matrix, Paint paint)

在这里你去！ （该参数形状可以轻松更换，如果你想的是，仅仅发表评论）：

Here you go! (The parameter shape can be replaced with ease, if you would like that, just leave a comment):

public static Matrix rotateMatrix(Bitmap bitmap, Shape shape, int rotation) {

        float scaleWidth = ((float) shape.getWidth()) / bitmap.getWidth();
        float scaleHeight = ((float) shape.getHeight()) / bitmap.getHeight();

        Matrix rotateMatrix = new Matrix();
        rotateMatrix.postScale(scaleWidth, scaleHeight);
        rotateMatrix.postRotate(rotation, shape.getWidth()/2, shape.getHeight()/2);
        rotateMatrix.postTranslate(shape.getX(), shape.getY());


        return rotateMatrix;

    }

注意：如果你想要一个动画旋转，旋转参数必须与新的价值观每一帧，例如更新。 1，然后2，然后3 ...

NB: If you want an animated rotation, the rotation parameter will have to be updated with new values every frame eg. 1 then 2 then 3 ...

这篇关于Android的位图旋转中心的周围无调整的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！