我有一个 GridView，里面有 ImageViews。我每行有 3 个。我可以使用 WRAP_CONTENT 和 scaleType = CENTER_CROP 正确设置宽度，但我不知道如何将 ImageView 的大小设置为正方形。这是我到目前为止所做的，除了高度之外似乎还可以，即“静态”：
imageView = new ImageView(context);
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setLayoutParams(new GridView.LayoutParams(GridView.LayoutParams.WRAP_CONTENT, 300));
我在适配器里面做。
最好的选择是对ImageView自己进行子类化，覆盖测量通道：
public class SquareImageView extends ImageView {
...
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int width = getMeasuredWidth();
setMeasuredDimension(width, width);
}
...
}
另一个答案工作正常。这只是 bertucci 的解决方案的扩展，以相对于 xml 膨胀布局制作具有正方形宽度和高度的 ImageView。
创建一个类，比如像这样扩展 ImageView 的 SquareImageView，
public class SquareImageView extends ImageView {
public SquareImageView(Context context) {
super(context);
}
public SquareImageView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public SquareImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int width = getMeasuredWidth();
setMeasuredDimension(width, width);
}
}
现在，在您的 xml 中执行此操作，
<com.packagepath.tothis.SquareImageView
android:id="@+id/Imageview"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
如果您需要不在程序中动态创建 ImageView，而是在 xml 中固定，那么此实现将很有帮助。
Even more simple:
public class SquareImageView extends ImageView {
...
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, widthMeasureSpec);
}
}
之前的几个答案是完全足够的。我只是在这里为@Andro Selva 和@a.bertucci 的解决方案添加了一个小优化：
这是一个微小的优化，但检查宽度和高度是否不同可能会阻止另一次测量通过。
public class SquareImageView extends ImageView {
public SquareImageView(Context context) {
super(context);
}
public SquareImageView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public SquareImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, widthMeasureSpec);
int width = getMeasuredWidth();
int height = getMeasuredHeight();
// Optimization so we don't measure twice unless we need to
if (width != height) {
setMeasuredDimension(width, width);
}
}
}
对于那些寻找 Kotlin 解决方案的人：
class SquareImageView @JvmOverloads constructor(
context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0, defStyleRes: Int = 0
) : ImageView(context, attrs, defStyleAttr, defStyleRes){
override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) = super.onMeasure(widthMeasureSpec, widthMeasureSpec)
}
指定宽度的 squareImageView：
public class SquareImageViewByWidth extends AppCompatImageView {
public SquareImageViewByWidth(Context context) {
super(context);
}
public SquareImageViewByWidth(Context context, AttributeSet attrs) {
super(context, attrs);
}
public SquareImageViewByWidth(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int width= getMeasuredWidth();
setMeasuredDimension(width, width);
}
...
}
指定高度的 squareImageView：
public class SquareImageViewByHeight extends AppCompatImageView {
public SquareImageViewByHeight(Context context) {
super(context);
}
public SquareImageViewByHeight(Context context, AttributeSet attrs) {
super(context, attrs);
}
public SquareImageViewByHeight(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int height = getMeasuredHeight();
setMeasuredDimension(height, height);
}
...
}
最小尺寸的 squareImageView：
public class SquareImageViewByMin extends AppCompatImageView {
public SquareImageViewByHeight(Context context) {
super(context);
}
public SquareImageViewByHeight(Context context, AttributeSet attrs) {
super(context, attrs);
}
public SquareImageViewByHeight(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int width = MeasureSpec.getSize(widthMeasureSpec);
int height = MeasureSpec.getSize(heightMeasureSpec);
int minSize = Math.min(width, height);
setMeasuredDimension(minSize, minSize);
}
...
}
如果有人希望视图不是方形的，而是按比例调整高度（例如，16/9 或 1/3），您可以这样做：
@Override
public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
heightMeasureSpec = MeasureSpec.makeMeasureSpec(getMeasuredWidth()/3, MeasureSpec.AT_MOST);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
单线解决方案 -
layout.setMinimumHeight(layout.getWidth());
Kotlin 的快速解决方案（Material.ShapeableImageView 可以改为 ImageView）
class SquareImageView @JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0
) : ShapeableImageView(context, attrs, defStyleAttr) {
override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec)
setMeasuredDimension(measuredWidth, measuredWidth)
}
}
这里都没有必要调用它的超类 for onMeasure。这是我的实现
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int width = MeasureSpec.getSize(widthMeasureSpec);
int height = MeasureSpec.getSize(heightMeasureSpec);
int size = Math.min(width, height);
setMeasuredDimension(size, size);
}