问题描述
需要自定义一个圆形imageview或者带有椭圆角的imageview，这个时候我们就自定义它。解决方案
先上图
声明：代码下载github https://github.com/pungrue26/SelectableRoundedImageView
imageview变换形状，本质上是将背景图片变化形状，加载到imageview，所以我们的重点是怎样写各种形状的drawable。
其实将图片切成各种形状，然后保存为png格式，也可以实现所要的效果
首先定义一些自定义属性，主要是是否是圆形，各个边角的弧度半径。
<declare-styleable name="SelectableRoundedImageView">
<attr name="sriv_left_top_corner_radius" format="dimension" />
<attr name="sriv_right_top_corner_radius" format="dimension" />
<attr name="sriv_left_bottom_corner_radius" format="dimension" />
<attr name="sriv_right_bottom_corner_radius" format="dimension" />
<attr name="sriv_border_width" format="dimension" />
<attr name="sriv_border_color" format="color" />
<attr name="sriv_oval" format="boolean" />
<attr name="android:scaleType" />
</declare-styleable>sriv_oval：是否是圆
android:scaleType系统定义的缩放类型
sriv_border_width：边界的宽
在布局文件使用自定义属性
<com.joooonho.SelectableRoundedImageView
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/image"
android:src="@drawable/photo1"
android:scaleType="centerCrop"
app:sriv_left_top_corner_radius="16dip"
app:sriv_right_top_corner_radius="0dip"
app:sriv_left_bottom_corner_radius="48dip"
app:sriv_right_bottom_corner_radius="16dip"
app:sriv_border_width="2dip"
app:sriv_border_color="#008fea"
app:sriv_oval="true" />切勿忘记xmlns命名空间的声明
然后我们在自定义view里面获取在布局空间定义的各种属性
public SelectableRoundedImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
TypedArray a = context.obtainStyledAttributes(attrs,
R.styleable.SelectableRoundedImageView, defStyle, 0);
final int index = a.getInt(R.styleable.SelectableRoundedImageView_android_scaleType, -1);
if (index >= 0) {
setScaleType(sScaleTypeArray[index]);
}
mLeftTopCornerRadius = a.getDimensionPixelSize(
R.styleable.SelectableRoundedImageView_sriv_left_top_corner_radius, 0);
mRightTopCornerRadius = a.getDimensionPixelSize(
R.styleable.SelectableRoundedImageView_sriv_right_top_corner_radius, 0);
mLeftBottomCornerRadius = a.getDimensionPixelSize(
R.styleable.SelectableRoundedImageView_sriv_left_bottom_corner_radius, 0);
mRightBottomCornerRadius = a.getDimensionPixelSize(
R.styleable.SelectableRoundedImageView_sriv_right_bottom_corner_radius, 0);
if (mLeftTopCornerRadius < 0.0f || mRightTopCornerRadius < 0.0f
|| mLeftBottomCornerRadius < 0.0f || mRightBottomCornerRadius < 0.0f) {
throw new IllegalArgumentException("radius values cannot be negative.");
}
mRadii = new float[] {
mLeftTopCornerRadius, mLeftTopCornerRadius,
mRightTopCornerRadius, mRightTopCornerRadius,
mRightBottomCornerRadius, mRightBottomCornerRadius,
mLeftBottomCornerRadius, mLeftBottomCornerRadius };
mBorderWidth = a.getDimensionPixelSize(
R.styleable.SelectableRoundedImageView_sriv_border_width, 0);
if (mBorderWidth < 0) {
throw new IllegalArgumentException("border width cannot be negative.");
}
mBorderColor = a
.getColorStateList(R.styleable.SelectableRoundedImageView_sriv_border_color);
if (mBorderColor == null) {
mBorderColor = ColorStateList.valueOf(DEFAULT_BORDER_COLOR);
}
isOval = a.getBoolean(R.styleable.SelectableRoundedImageView_sriv_oval, false);
a.recycle();
updateDrawable();
}其中，获取边角弧度
mLeftTopCornerRadius = a.getDimensionPixelSize(
R.styleable.SelectableRoundedImageView_sriv_left_top_corner_radius, 0);获取边框宽度
mBorderWidth = a.getDimensionPixelSize(
R.styleable.SelectableRoundedImageView_sriv_border_width, 0);获取是否是圆
isOval = a.getBoolean(R.styleable.SelectableRoundedImageView_sriv_oval, false);以上拿到自定义属性在后面都会用到
我们之前说过imageview核心就是背景图片，其根据背景图片的变化而变化，我们核心就是要定制背景图片。那我们怎样拿到背景图片并且将其变换成我们想要的形状呢。
这个时候自定义一个SelectableRoundedCornerDrawable继承Drawable
static class SelectableRoundedCornerDrawable extends Drawable {
private static final String TAG = "SelectableRoundedCornerDrawable";
private static final int DEFAULT_BORDER_COLOR = Color.BLACK;
private RectF mBounds = new RectF();
private RectF mBorderBounds = new RectF();
private final RectF mBitmapRect = new RectF();
private final int mBitmapWidth;
private final int mBitmapHeight;
private final Paint mBitmapPaint;
private final Paint mBorderPaint;
private BitmapShader mBitmapShader;
private float[] mRadii = new float[] { 0, 0, 0, 0, 0, 0, 0, 0 };
private float[] mBorderRadii = new float[] { 0, 0, 0, 0, 0, 0, 0, 0 };
private boolean mOval = false;
private float mBorderWidth = 0;
private ColorStateList mBorderColor = ColorStateList.valueOf(DEFAULT_BORDER_COLOR);
// Set default scale type to FIT_CENTER, which is default scale type of
// original ImageView.
private ScaleType mScaleType = ScaleType.FIT_CENTER;
private Path mPath = new Path();
private Bitmap mBitmap;
private boolean mBoundsConfigured = false;
public SelectableRoundedCornerDrawable(Bitmap bitmap, Resources r) {
mBitmap = bitmap;
mBitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
if (bitmap != null) {
mBitmapWidth = bitmap.getScaledWidth(r.getDisplayMetrics());
mBitmapHeight = bitmap.getScaledHeight(r.getDisplayMetrics());
} else {
mBitmapWidth = mBitmapHeight = -1;
}
mBitmapRect.set(0, 0, mBitmapWidth, mBitmapHeight);
mBitmapPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mBitmapPaint.setStyle(Paint.Style.FILL);
mBitmapPaint.setShader(mBitmapShader);
mBorderPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mBorderPaint.setStyle(Paint.Style.STROKE);
mBorderPaint.setColor(mBorderColor.getColorForState(getState(), DEFAULT_BORDER_COLOR));
mBorderPaint.setStrokeWidth(mBorderWidth);
}
public static SelectableRoundedCornerDrawable fromBitmap(Bitmap bitmap, Resources r) {
if (bitmap != null) {
return new SelectableRoundedCornerDrawable(bitmap, r);
} else {
return null;
}
}
public static Drawable fromDrawable(Drawable drawable, Resources r) {
if (drawable != null) {
if (drawable instanceof SelectableRoundedCornerDrawable) {
return drawable;
} else if (drawable instanceof LayerDrawable) {
LayerDrawable ld = (LayerDrawable) drawable;
final int num = ld.getNumberOfLayers();
for (int i = 0; i < num; i++) {
Drawable d = ld.getDrawable(i);
ld.setDrawableByLayerId(ld.getId(i), fromDrawable(d, r));
}
return ld;
}
Bitmap bm = drawableToBitmap(drawable);
if (bm != null) {
return new SelectableRoundedCornerDrawable(bm, r);
} else {
Log.w(TAG, "Failed to create bitmap from drawable!");
}
}
return drawable;
}
public static Bitmap drawableToBitmap(Drawable drawable) {
if (drawable == null) {
return null;
}
if (drawable instanceof BitmapDrawable) {
return ((BitmapDrawable) drawable).getBitmap();
}
Bitmap bitmap;
int width = Math.max(drawable.getIntrinsicWidth(), 2);
int height = Math.max(drawable.getIntrinsicHeight(), 2);
try {
bitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
drawable.draw(canvas);
} catch (IllegalArgumentException e) {
e.printStackTrace();
bitmap = null;
}
return bitmap;
}
@Override
public boolean isStateful() {
return mBorderColor.isStateful();
}
@Override
protected boolean onStateChange(int[] state) {
int newColor = mBorderColor.getColorForState(state, 0);
if (mBorderPaint.getColor() != newColor) {
mBorderPaint.setColor(newColor);
return true;
} else {
return super.onStateChange(state);
}
}
private void configureBounds(Canvas canvas) {
// I have discovered a truly marvelous explanation of this,
// which this comment space is too narrow to contain. :)
// If you want to understand what's going on here,
// See http://www.joooooooooonhokim.com/?p=289
Rect clipBounds = canvas.getClipBounds();
Matrix canvasMatrix = canvas.getMatrix();
if (ScaleType.CENTER == mScaleType) {
mBounds.set(clipBounds);
} else if (ScaleType.CENTER_CROP == mScaleType) {
applyScaleToRadii(canvasMatrix);
mBounds.set(clipBounds);
} else if (ScaleType.FIT_XY == mScaleType) {
Matrix m = new Matrix();
m.setRectToRect(mBitmapRect, new RectF(clipBounds), Matrix.ScaleToFit.FILL);
mBitmapShader.setLocalMatrix(m);
mBounds.set(clipBounds);
} else if (ScaleType.FIT_START == mScaleType || ScaleType.FIT_END == mScaleType
|| ScaleType.FIT_CENTER == mScaleType || ScaleType.CENTER_INSIDE == mScaleType) {
applyScaleToRadii(canvasMatrix);
mBounds.set(mBitmapRect);
} else if (ScaleType.MATRIX == mScaleType) {
applyScaleToRadii(canvasMatrix);
mBounds.set(mBitmapRect);
}
}
private void applyScaleToRadii(Matrix m) {
float[] values = new float[9];
m.getValues(values);
for (int i = 0; i < mRadii.length; i++) {
mRadii[i] = mRadii[i] / values[0];
}
}
private void adjustCanvasForBorder(Canvas canvas) {
Matrix canvasMatrix = canvas.getMatrix();
final float[] values = new float[9];
canvasMatrix.getValues(values);
final float scaleFactorX = values[0];
final float scaleFactorY = values[4];
final float translateX = values[2];
final float translateY = values[5];
final float newScaleX = mBounds.width()
/ (mBounds.width() + mBorderWidth + mBorderWidth);
final float newScaleY = mBounds.height()
/ (mBounds.height() + mBorderWidth + mBorderWidth);
canvas.scale(newScaleX, newScaleY);
if (ScaleType.FIT_START == mScaleType || ScaleType.FIT_END == mScaleType
|| ScaleType.FIT_XY == mScaleType || ScaleType.FIT_CENTER == mScaleType
|| ScaleType.CENTER_INSIDE == mScaleType || ScaleType.MATRIX == mScaleType) {
canvas.translate(mBorderWidth, mBorderWidth);
} else if (ScaleType.CENTER == mScaleType || ScaleType.CENTER_CROP == mScaleType) {
// First, make translate values to 0
canvas.translate(
-translateX / (newScaleX * scaleFactorX),
-translateY / (newScaleY * scaleFactorY));
// Then, set the final translate values.
canvas.translate(-(mBounds.left - mBorderWidth), -(mBounds.top - mBorderWidth));
}
}
private void adjustBorderWidthAndBorderBounds(Canvas canvas) {
Matrix canvasMatrix = canvas.getMatrix();
final float[] values = new float[9];
canvasMatrix.getValues(values);
final float scaleFactor = values[0];
float viewWidth = mBounds.width() * scaleFactor;
mBorderWidth = (mBorderWidth * mBounds.width()) / (viewWidth - (2 * mBorderWidth));
mBorderPaint.setStrokeWidth(mBorderWidth);
mBorderBounds.set(mBounds);
mBorderBounds.inset(- mBorderWidth / 2, - mBorderWidth / 2);
}
private void setBorderRadii() {
for (int i = 0; i < mRadii.length; i++) {
if (mRadii[i] > 0) {
mBorderRadii[i] = mRadii[i];
mRadii[i] = mRadii[i] - mBorderWidth;
}
}
}
@Override
public void draw(Canvas canvas) {
canvas.save();
if (!mBoundsConfigured) {
configureBounds(canvas);
if (mBorderWidth > 0) {
adjustBorderWidthAndBorderBounds(canvas);
setBorderRadii();
}
mBoundsConfigured = true;
}
if (mOval) {
if (mBorderWidth > 0) {
adjustCanvasForBorder(canvas);
mPath.addOval(mBounds, Path.Direction.CW);
canvas.drawPath(mPath, mBitmapPaint);
mPath.reset();
mPath.addOval(mBorderBounds, Path.Direction.CW);
canvas.drawPath(mPath, mBorderPaint);
} else {
mPath.addOval(mBounds, Path.Direction.CW);
canvas.drawPath(mPath, mBitmapPaint);
}
} else {
if (mBorderWidth > 0) {
adjustCanvasForBorder(canvas);
mPath.addRoundRect(mBounds, mRadii, Path.Direction.CW);
canvas.drawPath(mPath, mBitmapPaint);
mPath.reset();
mPath.addRoundRect(mBorderBounds, mBorderRadii, Path.Direction.CW);
canvas.drawPath(mPath, mBorderPaint);
} else {
mPath.addRoundRect(mBounds, mRadii, Path.Direction.CW);
canvas.drawPath(mPath, mBitmapPaint);
}
}
canvas.restore();
}
public void setCornerRadii(float[] radii) {
if (radii == null)
return;
if (radii.length != 8) {
throw new ArrayIndexOutOfBoundsException("radii[] needs 8 values");
}
for (int i = 0; i < radii.length; i++) {
mRadii[i] = radii[i];
}
}
@Override
public int getOpacity() {
return (mBitmap == null || mBitmap.hasAlpha() || mBitmapPaint.getAlpha() < 255) ? PixelFormat.TRANSLUCENT
: PixelFormat.OPAQUE;
}
@Override
public void setAlpha(int alpha) {
mBitmapPaint.setAlpha(alpha);
invalidateSelf();
}
@Override
public void setColorFilter(ColorFilter cf) {
mBitmapPaint.setColorFilter(cf);
invalidateSelf();
}
@Override
public void setDither(boolean dither) {
mBitmapPaint.setDither(dither);
invalidateSelf();
}
@Override
public void setFilterBitmap(boolean filter) {
mBitmapPaint.setFilterBitmap(filter);
invalidateSelf();
}
@Override
public int getIntrinsicWidth() {
return mBitmapWidth;
}
@Override
public int getIntrinsicHeight() {
return mBitmapHeight;
}
public float getBorderWidth() {
return mBorderWidth;
}
public void setBorderWidth(float width) {
mBorderWidth = width;
mBorderPaint.setStrokeWidth(width);
}
public int getBorderColor() {
return mBorderColor.getDefaultColor();
}
public void setBorderColor(int color) {
setBorderColor(ColorStateList.valueOf(color));
}
public ColorStateList getBorderColors() {
return mBorderColor;
}
/**
* Controls border color of this ImageView.
*
* @param colors
* The desired border color. If it's null, no border will be
* drawn.
*
*/
public void setBorderColor(ColorStateList colors) {
if (colors == null) {
mBorderWidth = 0;
mBorderColor = ColorStateList.valueOf(Color.TRANSPARENT);
mBorderPaint.setColor(Color.TRANSPARENT);
} else {
mBorderColor = colors;
mBorderPaint.setColor(mBorderColor.getColorForState(getState(),
DEFAULT_BORDER_COLOR));
}
}
public boolean isOval() {
return mOval;
}
public void setOval(boolean oval) {
mOval = oval;
}
public ScaleType getScaleType() {
return mScaleType;
}
public void setScaleType(ScaleType scaleType) {
if (scaleType == null) {
return;
}
mScaleType = scaleType;
}
}留个坑慢慢分析核心Drawable