ImageView 使用详解
程序员Android
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·
2020-12-02 02:45
和你一起终身学习,这里是程序员Android
经典好文推荐,通过阅读本文,您将收获以下知识点:
一、ImageView 的继承关系
二、ImageView 常用方法
三、ImageView 背景 间距属性设置
四、使用Bitmap 类型动态设置ImageView 资源
五、ImageView 图片倒影实现
六、ImageView 图片缩放实现
七、ImageView 圆角图片实现
八、Bitmap 与Drawable 转换工具类
一、ImageView 的继承关系
ImageView
的继承关系 如下:
java.lang.Object
↳ android.view.View
↳ android.widget.ImageView
二、ImageView 常用方法
ImageView
主要用于显示图像资源,Bitmap
或Drawable
资源,同时也常用于图片渲染调色,图片缩放剪裁等。
以下XML
代码段是使用ImageView
显示图像资源的常见示例:
1. 在xml
使用ImageView
控件
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@mipmap/ic_launcher"
/>
LinearLayout>
三、 ImageView 背景 间距属性设置
1. 在xml
使用ImageView
控件
<ImageView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/grey"
android:padding="5dp"
android:src="@drawable/ic_launcher" />
2. 实现效果如下:
padding background 属性设置
四、 使用Bitmap 类型动态设置ImageView 资源
1. 在xml
使用ImageView
控件
<ImageView
android:id="@+id/img_1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="5dp" />
2.java
类实现
// 1.从资源中获取Bitmap
ImageView mImageView1 = (ImageView) findViewById(R.id.img_1);
DrawableUtils.UseBitmap(this, mImageView1, R.drawable.gril);
3.DrawableUtils
类方法实现
// 1.从资源中获取Bitmap
public static void UseBitmap(Context context, ImageView imageView, int drawableId) {
Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(),
drawableId);
imageView.setImageBitmap(bitmap);
}
4. 实现效果如下:
bitmap 类型的图片
五、ImageView 图片倒影实现
1. 在xml
使用ImageView
控件
<ImageView
android:id="@+id/img_4"
android:layout_width="match_parent"
android:layout_height="200dp"
android:background="@color/grey"
android:padding="5dp" />
2. java
代码 实现效果
// 4.倒影图片
ImageView mImageView4 = (ImageView) findViewById(R.id.img_4);
mImageView4.setImageBitmap(DrawableUtils.CreateReflectionImageWithOrigin(
DrawableUtils.DrawableToBitmap(getResources().getDrawable(
R.drawable.img1))));
3. DrawableUtils
工具类的方法实现
// 5. Drawable----> Bitmap
public static Bitmap DrawableToBitmap(Drawable drawable) {
// 获取 drawable 长宽
int width = drawable.getIntrinsicWidth();
int heigh = drawable.getIntrinsicHeight();
drawable.setBounds(0, 0, width, heigh);
// 获取drawable的颜色格式
Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
: Bitmap.Config.RGB_565;
// 创建bitmap
Bitmap bitmap = Bitmap.createBitmap(width, heigh, config);
// 创建bitmap画布
Canvas canvas = new Canvas(bitmap);
// 将drawable 内容画到画布中
drawable.draw(canvas);
return bitmap;
}
4. 实现效果如下:
ImageView 倒影功能实现
六、ImageView 图片缩放实现
1. 在xml
使用ImageView
控件
<ImageView
android:id="@+id/img_2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="5dp" />
2. java
代码 实现效果
// 2. 图片缩放
ImageView mImageView2 = (ImageView) findViewById(R.id.img_2);
mImageView2.setImageDrawable(DrawableUtils.ZoomDrawable(getResources().getDrawable(R.drawable.img1),
240, 200));
3. DrawableUtils
工具类方法实现
// 9. drawable进行缩放 ---> bitmap 然后比对bitmap进行缩放
public static Drawable ZoomDrawable(Drawable drawable, int w, int h) {
int width = drawable.getIntrinsicWidth();
int height = drawable.getIntrinsicHeight();
// 调用5 中 drawable转换成bitmap
Bitmap oldbmp = DrawableToBitmap(drawable);
// 创建操作图片用的Matrix对象
Matrix matrix = new Matrix();
// 计算缩放比例
float sx = ((float) w / width);
float sy = ((float) h / height);
// 设置缩放比例
matrix.postScale(sx, sy);
// 建立新的bitmap,其内容是对原bitmap的缩放后的图
Bitmap newbmp = Bitmap.createBitmap(oldbmp, 0, 0, width, height,
matrix, true);
return new BitmapDrawable(newbmp);
}
4. 实现效果如下:
Imageview 缩放
七、ImageView 圆角图片 实现
1. 在xml
使用ImageView
控件
<ImageView
android:id="@+id/img_3"
android:layout_width="match_parent"
android:layout_height="150dp"
android:background="@color/grey"
android:padding="5dp" />
2.java
代码 实现效果
// 3. 圆角图片
ImageView mImageView3 = (ImageView) findViewById(R.id.img_3);
mImageView3.setImageBitmap(DrawableUtils.SetRoundCornerBitmap(
DrawableUtils.DrawableToBitmap(getResources().getDrawable(
R.drawable.img1)), 60));
3. DrawableUtils
工具类方法实现
// 6.圆角图片
public static Bitmap SetRoundCornerBitmap(Bitmap bitmap, float roundPx) {
int width = bitmap.getWidth();
int heigh = bitmap.getHeight();
// 创建输出bitmap对象
Bitmap outmap = Bitmap.createBitmap(width, heigh,
Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(outmap);
final int color = 0xff424242;
final Paint paint = new Paint();
final Rect rect = new Rect(0, 0, width, heigh);
final RectF rectf = new RectF(rect);
paint.setAntiAlias(true);
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(color);
canvas.drawRoundRect(rectf, roundPx, roundPx, paint);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, paint);
return outmap;
}
4. 实现效果如下:
圆角图片实现
八、Bitmap
与Drawable
转换工具类
Bitmap
与Drawable
转换常用工具类源代码如下:
public class DrawableUtils {
// 1.从资源中获取Bitmap
public static void UseBitmap(Context context, ImageView imageView, int drawableId) {
Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(),
drawableId);
imageView.setImageBitmap(bitmap);
}
// 2.Bitmap ---> byte[]
public byte[] BitmapToBytes(Bitmap bitmap) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);
return baos.toByteArray();
}
// 3.byte[] ---->bitmap
public Bitmap BytesToBitmap(byte[] b) {
if (b.length != 0) {
return BitmapFactory.decodeByteArray(b, 0, b.length);
} else {
return null;
}
}
// 4.Bitmap 缩放方法
public static Bitmap ZoomBitmap(Bitmap bitmap, int width, int heigh) {
int w = bitmap.getWidth();
int h = bitmap.getHeight();
Matrix matrix = new Matrix();
float scalewidth = (float) width / w;
float scaleheigh = (float) heigh / h;
matrix.postScale(scalewidth, scaleheigh);
Bitmap newBmp = Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);
return newBmp;
}
// 5. Drawable----> Bitmap
public static Bitmap DrawableToBitmap(Drawable drawable) {
// 获取 drawable 长宽
int width = drawable.getIntrinsicWidth();
int heigh = drawable.getIntrinsicHeight();
drawable.setBounds(0, 0, width, heigh);
// 获取drawable的颜色格式
Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
: Bitmap.Config.RGB_565;
// 创建bitmap
Bitmap bitmap = Bitmap.createBitmap(width, heigh, config);
// 创建bitmap画布
Canvas canvas = new Canvas(bitmap);
// 将drawable 内容画到画布中
drawable.draw(canvas);
return bitmap;
}
// 6.圆角图片
public static Bitmap SetRoundCornerBitmap(Bitmap bitmap, float roundPx) {
int width = bitmap.getWidth();
int heigh = bitmap.getHeight();
// 创建输出bitmap对象
Bitmap outmap = Bitmap.createBitmap(width, heigh,
Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(outmap);
final int color = 0xff424242;
final Paint paint = new Paint();
final Rect rect = new Rect(0, 0, width, heigh);
final RectF rectf = new RectF(rect);
paint.setAntiAlias(true);
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(color);
canvas.drawRoundRect(rectf, roundPx, roundPx, paint);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, paint);
return outmap;
}
// 7.获取带倒影的图片
public static Bitmap CreateReflectionImageWithOrigin(Bitmap bitmap) {
final int reflectionGapLine = 4;
int w = bitmap.getWidth();
int h = bitmap.getHeight();
Matrix matrix = new Matrix();
matrix.preScale(1, -1);
Bitmap reflectionImage = Bitmap.createBitmap(bitmap, 0, h / 2, w,
h / 2, matrix, false);
Bitmap bitmapWithReflection = Bitmap.createBitmap(w, (h + h / 2),
Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmapWithReflection);
canvas.drawBitmap(bitmap, 0, 0, null);
Paint deafalutPaint = new Paint();
canvas.drawRect(0, h, w, h + reflectionGapLine, deafalutPaint);
canvas.drawBitmap(reflectionImage, 0, h + reflectionGapLine, null);
Paint paint = new Paint();
LinearGradient shader = new LinearGradient(0, bitmap.getHeight(), 0,
bitmapWithReflection.getHeight() + reflectionGapLine, 0x70ffffff,
0x00ffffff, Shader.TileMode.CLAMP);
paint.setShader(shader);
// Set the Transfer mode to be porter duff and destination in
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
// Draw a rectangle using the paint with our linear gradient
canvas.drawRect(0, h, w, bitmapWithReflection.getHeight()
+ reflectionGapLine, paint);
return bitmapWithReflection;
}
// 8. bitmap ---Drawable
public static Drawable BitmapToDrawable(Bitmap bitmap, Context context) {
BitmapDrawable drawbale = new BitmapDrawable(context.getResources(),
bitmap);
return drawbale;
}
// 9. drawable进行缩放 ---> bitmap 然后比对bitmap进行缩放
public static Drawable ZoomDrawable(Drawable drawable, int w, int h) {
int width = drawable.getIntrinsicWidth();
int height = drawable.getIntrinsicHeight();
// 调用5 中 drawable转换成bitmap
Bitmap oldbmp = DrawableToBitmap(drawable);
// 创建操作图片用的Matrix对象
Matrix matrix = new Matrix();
// 计算缩放比例
float sx = ((float) w / width);
float sy = ((float) h / height);
// 设置缩放比例
matrix.postScale(sx, sy);
// 建立新的bitmap,其内容是对原bitmap的缩放后的图
Bitmap newbmp = Bitmap.createBitmap(oldbmp, 0, 0, width, height,
matrix, true);
return new BitmapDrawable(newbmp);
}
}
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