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本篇文章给大家分享的是有关怎么在Android中利用ImageView将图片进行圆形、圆角处理,小编觉得挺实用的,因此分享给大家学习,希望大家阅读完这篇文章后可以有所收获,话不多说,跟着小编一起来看看吧。
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基本思路是,自定义一个ImageView,通过重写onDraw方法画出一个圆形的图片来:
public class ImageViewPlus extends ImageView{ private Paint mPaintBitmap = new Paint(Paint.ANTI_ALIAS_FLAG); private Bitmap mRawBitmap; private BitmapShader mShader; private Matrix mMatrix = new Matrix(); public ImageViewPlus(Context context, AttributeSet attrs) { super(context, attrs); } @Override protected void onDraw(Canvas canvas) { Bitmap rawBitmap = getBitmap(getDrawable()); if (rawBitmap != null){ int viewWidth = getWidth(); int viewHeight = getHeight(); int viewMinSize = Math.min(viewWidth, viewHeight); float dstWidth = viewMinSize; float dstHeight = viewMinSize; if (mShader == null || !rawBitmap.equals(mRawBitmap)){ mRawBitmap = rawBitmap; mShader = new BitmapShader(mRawBitmap, TileMode.CLAMP, TileMode.CLAMP); } if (mShader != null){ mMatrix.setScale(dstWidth / rawBitmap.getWidth(), dstHeight / rawBitmap.getHeight()); mShader.setLocalMatrix(mMatrix); } mPaintBitmap.setShader(mShader); float radius = viewMinSize / 2.0f; canvas.drawCircle(radius, radius, radius, mPaintBitmap); } else { super.onDraw(canvas); } } private Bitmap getBitmap(Drawable drawable){ if (drawable instanceof BitmapDrawable){ return ((BitmapDrawable)drawable).getBitmap(); } else if (drawable instanceof ColorDrawable){ Rect rect = drawable.getBounds(); int width = rect.right - rect.left; int height = rect.bottom - rect.top; int color = ((ColorDrawable)drawable).getColor(); Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888); Canvas canvas = new Canvas(bitmap); canvas.drawARGB(Color.alpha(color), Color.red(color), Color.green(color), Color.blue(color)); return bitmap; } else { return null; } } }
分析一下代码:
canvas.drawCircle 决定了画出来的形状是圆形,而圆形的内容则是通过 mPaintBitmap.setShader 搞定的。
其中,BitmapShader需要设置Bitmap填充ImageView的方式(CLAMP:拉伸边缘, MIRROR:镜像, REPEAT:整图重复)。
这里其实设成什么不重要,因为我们实际需要的是将Bitmap按比例缩放成跟ImageView一样大,而不是预置的三种效果。
所以,别忘了 mMatrix.setScale 和 mShader.setLocalMatrix 一起用,将图片缩放一下。
四、支持边框
public class ImageViewPlus extends ImageView{ private Paint mPaintBitmap = new Paint(Paint.ANTI_ALIAS_FLAG); private Paint mPaintBorder = new Paint(Paint.ANTI_ALIAS_FLAG); private Bitmap mRawBitmap; private BitmapShader mShader; private Matrix mMatrix = new Matrix(); private float mBorderWidth = dip2px(15); private int mBorderColor = 0xFF0080FF; public ImageViewPlus(Context context, AttributeSet attrs) { super(context, attrs); } @Override protected void onDraw(Canvas canvas) { Bitmap rawBitmap = getBitmap(getDrawable()); if (rawBitmap != null){ int viewWidth = getWidth(); int viewHeight = getHeight(); int viewMinSize = Math.min(viewWidth, viewHeight); float dstWidth = viewMinSize; float dstHeight = viewMinSize; if (mShader == null || !rawBitmap.equals(mRawBitmap)){ mRawBitmap = rawBitmap; mShader = new BitmapShader(mRawBitmap, TileMode.CLAMP, TileMode.CLAMP); } if (mShader != null){ mMatrix.setScale((dstWidth - mBorderWidth * 2) / rawBitmap.getWidth(), (dstHeight - mBorderWidth * 2) / rawBitmap.getHeight()); mShader.setLocalMatrix(mMatrix); } mPaintBitmap.setShader(mShader); mPaintBorder.setStyle(Paint.Style.STROKE); mPaintBorder.setStrokeWidth(mBorderWidth); mPaintBorder.setColor(mBorderColor); float radius = viewMinSize / 2.0f; canvas.drawCircle(radius, radius, radius - mBorderWidth / 2.0f, mPaintBorder); canvas.translate(mBorderWidth, mBorderWidth); canvas.drawCircle(radius - mBorderWidth, radius - mBorderWidth, radius - mBorderWidth, mPaintBitmap); } else { super.onDraw(canvas); } } private Bitmap getBitmap(Drawable drawable){ if (drawable instanceof BitmapDrawable){ return ((BitmapDrawable)drawable).getBitmap(); } else if (drawable instanceof ColorDrawable){ Rect rect = drawable.getBounds(); int width = rect.right - rect.left; int height = rect.bottom - rect.top; int color = ((ColorDrawable)drawable).getColor(); Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888); Canvas canvas = new Canvas(bitmap); canvas.drawARGB(Color.alpha(color), Color.red(color), Color.green(color), Color.blue(color)); return bitmap; } else { return null; } } private int dip2px(int dipVal) { float scale = getResources().getDisplayMetrics().density; return (int)(dipVal * scale + 0.5f); } }
看代码中,加边框实际上就是用实心纯色的 Paint 画了一个圆边,在此基础上画上原来的头像即可。
需要的注意的地方有三个:
1)、圆框的半径不是 radius ,而应该是 radius - mBorderWidth / 2.0f 。想象着拿着笔去画线,线其实是画在右图中白色圈的位置,只不过它很粗。
2)、在ImageView大小不变的基础上,头像的实际大小要比没有边框的时候小了,所以 mMatrix.setScale 的时候要把边框的宽度去掉。
3)、画头像Bitmap的时候不能直接 canvas.drawCircle(radius, radius, radius - mBorderWidth, mPaintBitmap) ,这样你会发现头像的右侧和下方边缘被拉伸了(右图)
为什么呢?因为 Paint 默认是以左上角为基准开始绘制的,此时头像的实际区域是右图中的红框,而超过红框的部分(圆形的右侧和下方),自然被 TileMode.CLAMP效果沿边缘拉伸了。
所以,需要通过挪动坐标系的位置和调整圆心,才能把头像画在正确的区域(右图绿框)中。
五、更多玩法 —— 支持xml配置
既然有了边框,那如果想配置边框的宽度和颜色该如何是好呢?
基本上两个思路:
1)、给ImageViewPlus加上set接口,设置完成之后通过 invalidate(); 重绘一下即可;
2)、在xml里就支持配置一些自定义属性,这样用起来会方便很多。
这里重点说一下支持xml配置自定义属性。
自定义控件要支持xml配置自定义属性的话,首先需要在 \res\values 里去定义属性:
然后在ImageViewPlus的构造函数中去读取这些自定义属性:
private static final int DEFAULT_BORDER_COLOR = Color.TRANSPARENT; private static final int DEFAULT_BORDER_WIDTH = 0; public ImageViewPlus(Context context, AttributeSet attrs) { super(context, attrs); //取xml文件中设定的参数 TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.ImageViewPlus); mBorderColor = ta.getColor(R.styleable.ImageViewPlus_borderColor, DEFAULT_BORDER_COLOR); mBorderWidth = ta.getDimensionPixelSize(R.styleable.ImageViewPlus_borderWidth, dip2px(DEFAULT_BORDER_WIDTH)); ta.recycle(); }
在xml布局中使用自定义属性:
六、 圆角ImageView
其实原理上一样,把 canvas.drawCircle 对应改成 canvas.drawRoundRect 就OK了,直接贴代码吧:
public class ImageViewPlus extends ImageView{ /** * android.widget.ImageView */ public static final int TYPE_NONE = 0; /** * 圆形 */ public static final int TYPE_CIRCLE = 1; /** * 圆角矩形 */ public static final int TYPE_ROUNDED_RECT = 2; private static final int DEFAULT_TYPE = TYPE_NONE; private static final int DEFAULT_BORDER_COLOR = Color.TRANSPARENT; private static final int DEFAULT_BORDER_WIDTH = 0; private static final int DEFAULT_RECT_ROUND_RADIUS = 0; private int mType; private int mBorderColor; private int mBorderWidth; private int mRectRoundRadius; private Paint mPaintBitmap = new Paint(Paint.ANTI_ALIAS_FLAG); private Paint mPaintBorder = new Paint(Paint.ANTI_ALIAS_FLAG); private RectF mRectBorder = new RectF(); private RectF mRectBitmap = new RectF(); private Bitmap mRawBitmap; private BitmapShader mShader; private Matrix mMatrix = new Matrix(); public ImageViewPlus(Context context, AttributeSet attrs) { super(context, attrs); //取xml文件中设定的参数 TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.ImageViewPlus); mType = ta.getInt(R.styleable.ImageViewPlus_type, DEFAULT_TYPE); mBorderColor = ta.getColor(R.styleable.ImageViewPlus_borderColor, DEFAULT_BORDER_COLOR); mBorderWidth = ta.getDimensionPixelSize(R.styleable.ImageViewPlus_borderWidth, dip2px(DEFAULT_BORDER_WIDTH)); mRectRoundRadius = ta.getDimensionPixelSize(R.styleable.ImageViewPlus_rectRoundRadius, dip2px(DEFAULT_RECT_ROUND_RADIUS)); ta.recycle(); } @Override protected void onDraw(Canvas canvas) { Bitmap rawBitmap = getBitmap(getDrawable()); if (rawBitmap != null && mType != TYPE_NONE){ int viewWidth = getWidth(); int viewHeight = getHeight(); int viewMinSize = Math.min(viewWidth, viewHeight); float dstWidth = mType == TYPE_CIRCLE ? viewMinSize : viewWidth; float dstHeight = mType == TYPE_CIRCLE ? viewMinSize : viewHeight; float halfBorderWidth = mBorderWidth / 2.0f; float doubleBorderWidth = mBorderWidth * 2; if (mShader == null || !rawBitmap.equals(mRawBitmap)){ mRawBitmap = rawBitmap; mShader = new BitmapShader(mRawBitmap, TileMode.CLAMP, TileMode.CLAMP); } if (mShader != null){ mMatrix.setScale((dstWidth - doubleBorderWidth) / rawBitmap.getWidth(), (dstHeight - doubleBorderWidth) / rawBitmap.getHeight()); mShader.setLocalMatrix(mMatrix); } mPaintBitmap.setShader(mShader); mPaintBorder.setStyle(Paint.Style.STROKE); mPaintBorder.setStrokeWidth(mBorderWidth); mPaintBorder.setColor(mBorderWidth > 0 ? mBorderColor : Color.TRANSPARENT); if (mType == TYPE_CIRCLE){ float radius = viewMinSize / 2.0f; canvas.drawCircle(radius, radius, radius - halfBorderWidth, mPaintBorder); canvas.translate(mBorderWidth, mBorderWidth); canvas.drawCircle(radius - mBorderWidth, radius - mBorderWidth, radius - mBorderWidth, mPaintBitmap); } else if (mType == TYPE_ROUNDED_RECT){ mRectBorder.set(halfBorderWidth, halfBorderWidth, dstWidth - halfBorderWidth, dstHeight - halfBorderWidth); mRectBitmap.set(0.0f, 0.0f, dstWidth - doubleBorderWidth, dstHeight - doubleBorderWidth); float borderRadius = mRectRoundRadius - halfBorderWidth > 0.0f ? mRectRoundRadius - halfBorderWidth : 0.0f; float bitmapRadius = mRectRoundRadius - mBorderWidth > 0.0f ? mRectRoundRadius - mBorderWidth : 0.0f; canvas.drawRoundRect(mRectBorder, borderRadius, borderRadius, mPaintBorder); canvas.translate(mBorderWidth, mBorderWidth); canvas.drawRoundRect(mRectBitmap, bitmapRadius, bitmapRadius, mPaintBitmap); } } else { super.onDraw(canvas); } } private int dip2px(int dipVal) { float scale = getResources().getDisplayMetrics().density; return (int)(dipVal * scale + 0.5f); } private Bitmap getBitmap(Drawable drawable){ if (drawable instanceof BitmapDrawable){ return ((BitmapDrawable)drawable).getBitmap(); } else if (drawable instanceof ColorDrawable){ Rect rect = drawable.getBounds(); int width = rect.right - rect.left; int height = rect.bottom - rect.top; int color = ((ColorDrawable)drawable).getColor(); Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888); Canvas canvas = new Canvas(bitmap); canvas.drawARGB(Color.alpha(color), Color.red(color), Color.green(color), Color.blue(color)); return bitmap; } else { return null; } } }
以上就是怎么在Android中利用ImageView将图片进行圆形、圆角处理,小编相信有部分知识点可能是我们日常工作会见到或用到的。希望你能通过这篇文章学到更多知识。更多详情敬请关注创新互联行业资讯频道。