Android 开发中收容器

Bitmap 裁剪图片周边透明区域

//方法1：
public static Bitmap trimBitmap(Bitmap bitmap) {
        int top = 0;
        int left = 0;
        int right = bitmap.getWidth() - 1;
        int bottom = 0;

        for (int w = bitmap.getWidth() / 2; w < bitmap.getWidth(); w += 2) {
            int h = 0;
            for (h = 0; h < bitmap.getHeight(); h+=2) {
                int color = bitmap.getPixel(w, h);
                if (color != 0) {
                    if (top == 0) {
                        top = h;
                    }
                    top = Math.min(top, h);
                    break;
                }
            }

            if (h >= bitmap.getHeight() - 1) {
                right = w;
                break;
            }
        }

        for (int w = bitmap.getWidth() / 2 - 1; w >= 0; w -= 2) {
            int h = 0;
            for (h = 0; h < bitmap.getHeight(); h+=2) {
                int color = bitmap.getPixel(w, h);
                if (color != 0) {
                    if (top == 0) {
                        top = h;
                    }
                    top = Math.min(top, h);
                    break;
                }
            }

            if (h >= bitmap.getHeight() - 1) {
                left = w;
                break;
            }
        }

        for (int w = left; w <= right; w++) {
            for (int h = bitmap.getHeight() - 1; h >= top; h--) {
                int color = bitmap.getPixel(w, h);
                if (color != 0) {
                    bottom = Math.max(bottom, h);
                    break;
                }
            }
        }

        //对边界值做一次判断，保证严谨
        int x = (int) Math.max(left  , 0f);
        int y = (int) Math.max(top  , 0f);
        int w = (int) Math.min(right - left  , bitmap.getWidth() - x);
        int h = (int) Math.min(bottom - top  , bitmap.getHeight() - y);
        if (x + w > bitmap.getWidth()) {
            x = 0;
            w = bitmap.getWidth();
        }

        if (y + h > bitmap.getHeight()) {
            y = 0;
            h = bitmap.getHeight();
        }
        return Bitmap.createBitmap(bitmap, x, y, w, h);
    }
//方法2：
public static Bitmap TrimBitmap(Bitmap bmp) {
        int imgHeight = bmp.getHeight();
        int imgWidth = bmp.getWidth(); 
        //TRIM WIDTH - LEFT
        int startWidth = 0;
        for (int x = 0; x < imgWidth; x++) {
            if (startWidth == 0) {
                for (int y = 0; y < imgHeight; y++) {
                    if (bmp.getPixel(x, y) != Color.TRANSPARENT) {
                        startWidth = x;
                        break;
                    }
                }
            } else break;
        }
        //TRIM WIDTH - RIGHT
        int endWidth = 0;
        for (int x = imgWidth - 1; x >= 0; x--) {
            if (endWidth == 0) {
                for (int y = 0; y < imgHeight; y++) {
                    if (bmp.getPixel(x, y) != Color.TRANSPARENT) {
                        endWidth = x;
                        break;
                    }
                }
            } else break;
        }
        //TRIM HEIGHT - TOP
        int startHeight = 0;
        for (int y = 0; y < imgHeight; y++) {
            if (startHeight == 0) {
                for (int x = 0; x < imgWidth; x++) {
                    if (bmp.getPixel(x, y) != Color.TRANSPARENT) {
                        startHeight = y;
                        break;
                    }
                }
            } else break;
        }
        //TRIM HEIGHT - BOTTOM
        int endHeight = 0;
        for (int y = imgHeight - 1; y >= 0; y--) {
            if (endHeight == 0) {
                for (int x = 0; x < imgWidth; x++) {
                    if (bmp.getPixel(x, y) != Color.TRANSPARENT) {
                        endHeight = y;
                        break;
                    }
                }
            } else break;
        }
        return Bitmap.createBitmap(bmp, startWidth, startHeight, endWidth - startWidth, endHeight - startHeight);
    }

Matrix 获取当前旋转角度值和当前缩放值

    private float[] matrixValues = new float[9];

    private float getMatrixValue(@NonNull Matrix matrix, @IntRange(from = 0, to = 9) int valueIndex) {
        matrix.getValues(matrixValues);
        return matrixValues[valueIndex];
    }
    //角度
    private float getMatrixAngle(@NonNull Matrix matrix) {
        return (float) -(Math.atan2(getMatrixValue(matrix, Matrix.MSKEW_X),
                getMatrixValue(matrix, Matrix.MSCALE_X)) * (180 / Math.PI));
    }
    //缩放
    private float getMatrixScale(@NonNull Matrix matrix) {
        return (float) Math.sqrt(Math.pow(getMatrixValue(matrix, Matrix.MSCALE_X), 2) + Math.pow(
                getMatrixValue(matrix, Matrix.MSKEW_Y), 2));
    }

AndroidBug5497Workaround

import android.app.Activity;
import android.graphics.Rect;
import android.os.Build;
import android.view.View;
import android.view.ViewTreeObserver;
import android.widget.FrameLayout;

public class AndroidBug5497Workaround {
    public static void assistActivity(Activity activity) {
        new AndroidBug5497Workaround(activity);
    }
    private View mChildOfContent;
    private int usableHeightPrevious;
    private FrameLayout.LayoutParams frameLayoutParams;
    private int contentHeight;
    private   boolean isfirst = true;
    private   Activity activity;
    private  int statusBarHeight;

    private AndroidBug5497Workaround(Activity activity) {
        //获取状态栏的高度
        int resourceId = activity.getResources().getIdentifier("status_bar_height", "dimen", "android");
        statusBarHeight = activity.getResources().getDimensionPixelSize(resourceId)+5;
        this.activity = activity;
        FrameLayout content = (FrameLayout)activity.findViewById(android.R.id.content);
        mChildOfContent = content.getChildAt(0);

        //界面出现变动都会调用这个监听事件
        mChildOfContent.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            public void onGlobalLayout() {
                if (isfirst) {
                    contentHeight = mChildOfContent.getHeight();//兼容华为等机型
                    isfirst = false;
                }
                possiblyResizeChildOfContent();
            }
        });

        frameLayoutParams = (FrameLayout.LayoutParams)
                mChildOfContent.getLayoutParams();
    }

    //重新调整跟布局的高度
    private void possiblyResizeChildOfContent() {

        int usableHeightNow = computeUsableHeight();

        //当前可见高度和上一次可见高度不一致 布局变动
        if (usableHeightNow != usableHeightPrevious) {
            //int usableHeightSansKeyboard2 = mChildOfContent.getHeight();//兼容华为等机型
            int usableHeightSansKeyboard = mChildOfContent.getRootView().getHeight();
            int heightDifference = usableHeightSansKeyboard - usableHeightNow;
            if (heightDifference > (usableHeightSansKeyboard / 4)) {
                // keyboard probably just became visible
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT){
                    //frameLayoutParams.height = usableHeightSansKeyboard - heightDifference;
                    frameLayoutParams.height = usableHeightSansKeyboard - heightDifference + statusBarHeight;
                } else {
                    frameLayoutParams.height = usableHeightSansKeyboard -heightDifference;
                }
            } else {
                frameLayoutParams.height = contentHeight;
            }

            mChildOfContent.requestLayout();
            usableHeightPrevious = usableHeightNow;
        }
    }
    /**     
    * 计算mChildOfContent可见高度     
    * @return     
    */
    private int computeUsableHeight() {
        Rect r = new Rect();
        mChildOfContent.getWindowVisibleDisplayFrame(r);
        return (r.bottom - r.top);
    }
}

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