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Loooong時間查看器，終於輪到在這裏註冊StackOverflow！自定義動畫可繪製電池消耗
經過很長的時間尋找一種方式做在Android上的ViewGroup的滾動背景，我已經開發了以下內容：
public class SlidingDrawable extends Drawable implements Drawable.Callback {
private static final String TAG = "SlidingDraw";
private static float STEP_SIZE = 1.0f;
private BitmapDrawable mBitmap;
private Context mContext;
private float mPosX;
private int mBitmapWidth;
private Runnable mInvalidater;
private Handler mHandler;
public SlidingDrawable(Context c){
mContext = c;
// use this as the callback as we're implementing the interface
setCallback(this);
mHandler = new Handler();
mInvalidater = new Runnable(){
@Override
public void run(){
// decrement the drawables step size
mPosX -= SlidingDrawable.STEP_SIZE;
/*
* Check to see if the current position is at point where it should
* loop. If so, reset back to 0 to restart
*/
if(Math.abs(mPosX) >= mBitmapWidth) mPosX = 0;
// redraw
invalidateDrawable(null);
}
};
}
public static void setStepSize(float newSize){
SlidingDrawable.STEP_SIZE = newSize;
}
public void createBitmap(String path, ViewGroup parent){
// height of the parent container
int height = parent.getHeight();
/* Initialize local variables
* bgBitmap - the resulting bitmap to send into SlidingDrawable instance
* imageStream - raw bitmap data to be decoded into bgBitmap
*/
WindowManager wMgr = (WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE);
int mScreenWidth = wMgr.getDefaultDisplay().getWidth();
InputStream imageStream;
Matrix imgMatrix = new Matrix();
Bitmap bitmap = null;
try {
imageStream = mContext.getAssets().open(path);
// create a temporary bitmap object for basic data
Bitmap temp = BitmapFactory.decodeStream(imageStream);
int width = temp.getWidth();
// find the width difference as a percentage to apply to the
// transformation matrix
float widthDifference = ((float)mScreenWidth)/(float)(width/2);
imgMatrix.postScale(widthDifference, 0, 0f, 0f);
// create a copy of the bitmap, scaled correctly to maintain loop
bitmap = Bitmap.createScaledBitmap(temp, (int)(width * widthDifference), height, true);
// recycle the temp bitmap
temp.recycle();
} catch (IOException e) {
e.printStackTrace();
}
mBitmap = new BitmapDrawable(bitmap);
// required
mBitmapWidth = getIntrinsicWidth()/2;
Rect bounds = new Rect(0, 0, getIntrinsicWidth(), getIntrinsicHeight());
setBounds(bounds);
}
@Override
public void draw(Canvas canvas) {
canvas.drawBitmap(mBitmap.getBitmap(), mPosX, 0f, null);
scheduleDrawable(this, mInvalidater, SystemClock.uptimeMillis());
}
@Override
public int getOpacity() {
return PixelFormat.OPAQUE;
}
@Override
public void scheduleDrawable(Drawable who, Runnable what, long when) {
mHandler.postAtTime(what, who, when);
}
@Override
public void unscheduleDrawable(Drawable who, Runnable what) {
mHandler.removeCallbacks(what, who);
}
@Override
public void invalidateDrawable(Drawable who) {
invalidateSelf();
}
/*
* Methods not directly used or called omitted
*
*/
}
它在活動等中使用所以：
@Override
public void onWindowFocusChanged(boolean focus){
// set the background of the root view of main.xml
SlidingDrawable drawable = new SlidingDrawable(getApplicationContext());
drawable.createBitmap("bgimg/basebg.jpg", mRoot);
mRoot.setBackgroundDrawable(drawable);
}
長話短說，basebg.jpg圖像是一個大致1600x480的圖像圖像。 SlidingDrawable的構造函數用於縮放和移動yaddah yaddah。有用。
現在，問題是，這樣做似乎效率低下。我似乎無法找到關於這種實現的很多信息，所以我在黑暗中我可以削減CPU週期，或者即使我正確使用方法調用。
我的問題包括：
- 是更好地drawBitmap而不是使用setTranslate（）或的postTranslate和借鑑使用矩陣位圖？
- 使用drawBitmap還是使用諸如translate（），save（）和restore（）之類的畫布函數會更好嗎？
- draw（）方法被調用的速率是多少，並且有沒有辦法將它限制爲24 FPS o limit redraws？
- 這些東西的「何時」參數到底是什麼？傳遞SystemClock.uptimeMillis（）是唯一有效的工作，並試圖通過添加一個「+ 100」或每隔100毫秒觸發一次來延遲它就會造成口吃。
，我可以......我把它留給StackOverflow的現在:)