我们能从Android的视图中以编程方式创建画布吗？
我们能从Android的视图中以编程方式创建画布吗？
提问于 2022-10-14 09:06:36
我正在尝试从已经存在的视图创建一个虚拟视图。
原始图像：
需要创建这样的虚拟视图。
我试过用油漆和帆布。
public class MyView extends View {
Paint paint;
Path path;
public MyView(Context context) {
super(context);
init();
}
public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public MyView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init(){
paint = new Paint();
paint.setColor(Color.BLUE);
paint.setStrokeWidth(10);
paint.setStyle(Paint.Style.STROKE);
}
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
canvas.drawRect(30, 50, 200, 350, paint);
// canvas.drawRect(100, 100, 300, 400, paint);
//drawRect(left, top, right, bottom, paint)
}
}但我不能这样画。因为某些时间图像将是圆圈或椭圆或任何形状。因此，我需要扣除现有的视图，并绘制相同的新视图。有人能帮我从现有视图创建虚拟视图吗？
我试着这样做只为微光动画。对于facebook shimmer，我需要给出shimmerFramelayout内部的视图。但我的观点将是动态的。因此，我需要每次都以编程的方式创建一个虚拟视图。对于facebook Shimmer：
<com.facebook.shimmer.ShimmerFrameLayout
android:id="@+id/shimmerLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:ignore="MissingConstraints">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<!--add several shimmer placeholder layout -->
<include layout="@layout/shimmer_placeholder_layout"></include>
<include layout="@layout/shimmer_placeholder_layout"></include>
<include layout="@layout/shimmer_placeholder_layout"></include>
</LinearLayout>
</com.facebook.shimmer.ShimmerFrameLayout>这里shimmer_placeholder_layout是静态视图。我需要创建动态视图。
回答 1
Stack Overflow用户
回答已采纳
发布于 2022-10-17 09:25:31
终于找到解决办法了。
在这里，我附上了解决方案，因为有人会从中受益。MyView类：
public class MyView extends View {
Paint paint;
ViewGroup viewGroup;
Context context;
List<Rect> rectList = new ArrayList<>();
public MyView(Context context, ViewGroup viewGroup) {
super(context);
this.viewGroup = viewGroup;
this.context = context;
init();
}
public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public MyView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init() {
paint = new Paint();
paint.setColor(context.getResources().getColor(R.color.gray));
paint.setStrokeWidth(10);
paint.setStyle(Paint.Style.FILL);
for (int i = 0; i < viewGroup.getChildCount(); ++i) {
View child = viewGroup.getChildAt(i);
Rect rect = new Rect();
int x = (int) child.getX() - dpToPx(20);
int y = (int) child.getY() - dpToPx(20);
rect.left = x;
rect.top = y;
rect.right = x + child.getWidth();
rect.bottom = y + child.getHeight();
rectList.add(rect);
}
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
for (Rect rect : rectList) {
canvas.drawRect(rect, paint);
}
}
public static int dpToPx(int dp) {
return (int) (dp * Resources.getSystem().getDisplayMetrics().density);
}
}我的MainActivity：
ConstraintLayout constraintLayout;
ImageView imageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
constraintLayout = findViewById(R.id.parent_view);
imageView = findViewById(R.id.item_profile_img);
constraintLayout.post(() -> {
ShimmerFrameLayout shimmerFrameLayout = new ShimmerFrameLayout(MainActivity.this);
Shimmer shimmer = new Shimmer.ColorHighlightBuilder()
.setDuration(2000)
.setBaseAlpha(0.9f)
.setHighlightAlpha(0.93f)
.setWidthRatio(1.5f)
.setDirection(Shimmer.Direction.RIGHT_TO_LEFT)
.setAutoStart(true)
.setBaseColor(getColor(android.R.color.darker_gray))
.setBaseColor(getColor(android.R.color.darker_gray))
.setHighlightColor(getColor(android.R.color.white))
.build();
shimmerFrameLayout.setShimmer(shimmer);
shimmerFrameLayout.addView(new MyView(MainActivity.this,constraintLayout));
constraintLayout.addView(shimmerFrameLayout);
shimmerFrameLayout.startShimmer();
});
}我的activity_main.xml：
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
tools:ignore="HardcodedText,MissingConstraints"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<androidx.constraintlayout.widget.ConstraintLayout
tools:ignore="HardcodedText,MissingConstraints"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="20dp"
android:id="@+id/parent_view">
<ImageView
android:id="@+id/item_profile_img"
android:layout_width="100dp"
android:layout_height="100dp"
android:src="@drawable/ic_launcher_background"
app:layout_constraintTop_toTopOf="parent"
tools:ignore="ContentDescription,MissingConstraints" />
<TextView
android:id="@+id/item_student_name_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="15dp"
android:text="Student name"
android:textStyle="bold"
app:layout_constraintStart_toEndOf="@+id/item_profile_img" />
<TextView
android:id="@+id/item_student_college"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="15dp"
android:layout_marginTop="8dp"
android:text="Student college"
app:layout_constraintStart_toEndOf="@+id/item_profile_img"
app:layout_constraintTop_toBottomOf="@+id/item_student_name_title" />
<TextView
android:id="@+id/item_student_specialization"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="15dp"
android:layout_marginTop="8dp"
android:text="Student specialization"
app:layout_constraintStart_toEndOf="@+id/item_profile_img"
app:layout_constraintTop_toBottomOf="@+id/item_student_college" />
<TextView
android:id="@+id/item_student_description"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="15dp"
android:layout_marginTop="8dp"
android:text="Student description"
app:layout_constraintTop_toBottomOf="@+id/item_profile_img"
tools:ignore="MissingConstraints" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/74066895
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