按钮的背景不显示

Question

不显示背景。如果按钮没有背景，则显示 OK<?xml version="1.0" encoding="utf-8"?><android.support.constraint.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"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:background="?attr/colorBackgroundFloating"    tools:context=".MainActivity"    tools:layout_editor_absoluteY="25dp">    <Button        android:id="@+id/button_1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerInParent="true"        android:layout_weight="1"        android:background="@drawable/my_round_button"        android:onClick="onClick"        android:text="@string/button_1"        android:visibility="visible"        app:layout_constraintBottom_toBottomOf="parent"        app:layout_constraintEnd_toEndOf="parent"        app:layout_constraintStart_toStartOf="parent"        app:layout_constraintTop_toTopOf="parent" /></android.support.constraint.ConstraintLayout>当应用程序按钮没有背景时，按钮看起来像 ractanglemy_round_button<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="http://schemas.android.com/apk/res/android"    android:shape="ring">    <solid android:color="#FFFFFF" /></shape>怎么了？按钮应该看起来像戒指

Answer 1

我建议您创建自定义视图，它以圆形的形式呈现视图，并根据我们从布局传递的宽度/高度。它更有活力。

我确实喜欢Son Truong建议的答案，但这似乎不是更通用，因为我们需要硬编码尺寸宽度/高度。

第一步：创建主题style.xml

<declare-styleable name="CircleCompatTextView">

    <attr name="cctv_stroke_width" format="dimension" />

    <attr name="cctv_background_color" format="color" />

    <attr name="cctv_border_color" format="color" />

</declare-styleable>

第 2 步：创建自定义视图。

public class CircleCompatTextView extends AppCompatTextView {

    private final Paint paintCircle = new Paint();

    private final Paint paintStroke = new Paint();

    private final Resources resources;

    private int strokeWidth;

    private int bgColor;

    private int borderColor;

    private int cxCy;

    public CircleCompatTextView(Context context, AttributeSet attrs) {

        super(context, attrs);

        resources = context.getResources();

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CircleCompatTextView);

        strokeWidth = a.getDimensionPixelSize(R.styleable.CircleCompatTextView_cctv_stroke_width, 1);

        bgColor = a.getColor(R.styleable.CircleCompatTextView_cctv_background_color, resources.getColor(android.R.color.transparent));

        borderColor = a.getColor(R.styleable.CircleCompatTextView_cctv_border_color, resources.getColor(android.R.color.background_dark));

        a.recycle();

        init();

    }

    private void init() {

        paintCircle.setColor(bgColor);

        paintCircle.setFlags(Paint.ANTI_ALIAS_FLAG);

        paintStroke.setColor(borderColor);

        paintStroke.setStyle(Paint.Style.STROKE);

        paintStroke.setStrokeWidth(strokeWidth);

        paintStroke.setFlags(Paint.ANTI_ALIAS_FLAG);

    }

    @Override

    public void draw(Canvas canvas) {

        canvas.drawCircle(cxCy, cxCy, cxCy - strokeWidth / 2, paintStroke);

        canvas.drawCircle(cxCy, cxCy, cxCy - strokeWidth / 2, paintCircle);

        super.draw(canvas);

    }

    @Override

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        int width = getMeasuredWidth();

        int height = getMeasuredHeight();

        int size = ((height > width) ? height : width);

        cxCy = size / 2;

        setMeasuredDimension(size, size);

    }

}

第三步：自定义视图的使用

<CircleCompatTextView

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:gravity="center|center_vertical"

        android:padding="16dp"

        android:textAlignment="center"

        app:cctv_background_color="@android:color/transparent"

        app:cctv_border_color="@android:color/background_dark"

        app:cctv_stroke_width="2dp" />

这是输出