Android圖文居中顯示控制元件使用方法詳解
阿新 • • 發佈:2020-09-07
最近專案中用到了文字圖示的按鈕,需要居中顯示,如果用TextView實現的方式,必須同時設定padding和drawablePadding。如下:
<androidx.appcompat.widget.AppCompatTextView android:layout_width="200dp" android:layout_height="wrap_content" android:drawableLeft="@drawable/ic_xxx" android:drawablePadding="-60dp" android:minHeight="48dp" android:gravity="center" android:padding="80dp" />
這種方式需要自己做精確計算。比較麻煩。另外還有一種方式就是用線性佈局包裹ImageView和TextView,但這樣會增加布局層級。於是自己封裝了一個控制元件DrawableCenterTextView。
attrs.xml檔案中定義屬性:
<declare-styleable name="DrawableCenterTextView"> <attr name="android:text" /> <attr name="android:textColor" /> <attr name="android:textSize" /> <attr name="android:textStyle" /> <attr name="android:drawablePadding" /> <attr name="android:drawableLeft" /> <attr name="android:drawableTop" /> <attr name="android:drawableRight" /> <attr name="android:drawableBottom" /> </declare-styleable>
對應的Java程式碼如下:
public class DrawableCenterTextView extends View { static final int LEFT = 0; static final int TOP = 1; static final int RIGHT = 2; static final int BOTTOM = 3; private CharSequence mText; private ColorStateList mTextColor; private float mTextSize; private int mTextStyle; private int mDrawablePadding; private Drawable[] mCompoundDrawables; private Rect mTextBounds; private Rect mDrawableLeftBounds; private Rect mDrawableTopBounds; private Rect mDrawableRightBounds; private Rect mDrawableBottomBounds; private TextPaint mTextPaint; public DrawableCenterTextView(Context context) { this(context,null); } public DrawableCenterTextView(Context context,AttributeSet attrs) { this(context,attrs,0); } public DrawableCenterTextView(Context context,AttributeSet attrs,int defStyleAttr) { super(context,defStyleAttr); Drawable drawableLeft = null,drawableTop = null,drawableRight = null,drawableBottom = null; TypedArray ta = context.obtainStyledAttributes(attrs,R.styleable.DrawableCenterTextView,defStyleAttr,0); mText = ta.getText(R.styleable.DrawableCenterTextView_android_text); mTextColor = ta.getColorStateList(R.styleable.DrawableCenterTextView_android_textColor); mTextSize = ta.getDimensionPixelSize(R.styleable.DrawableCenterTextView_android_textSize,15); mTextStyle = ta.getInt(R.styleable.DrawableCenterTextView_android_textStyle,0); drawableLeft = ta.getDrawable(R.styleable.DrawableCenterTextView_android_drawableLeft); drawableTop = ta.getDrawable(R.styleable.DrawableCenterTextView_android_drawableTop); drawableRight = ta.getDrawable(R.styleable.DrawableCenterTextView_android_drawableRight); drawableBottom = ta.getDrawable(R.styleable.DrawableCenterTextView_android_drawableBottom); mDrawablePadding = ta.getDimensionPixelSize(R.styleable.DrawableCenterTextView_android_drawablePadding,0); ta.recycle(); if (mTextColor == null) { mTextColor = ColorStateList.valueOf(0xFF000000); } mTextPaint = new TextPaint(Paint.ANTI_ALIAS_FLAG); mTextPaint.density = getResources().getDisplayMetrics().density; mTextPaint.setTextSize(mTextSize); setTypeface(Typeface.create(Typeface.DEFAULT,mTextStyle)); setCompoundDrawablesWithIntrinsicBounds(drawableLeft,drawableTop,drawableRight,drawableBottom); } @Override protected void onMeasure(int widthMeasureSpec,int heightMeasureSpec) { int widthMode = MeasureSpec.getMode(widthMeasureSpec); int heightMode = MeasureSpec.getMode(heightMeasureSpec); int widthSize = MeasureSpec.getSize(widthMeasureSpec); int heightSize = MeasureSpec.getSize(heightMeasureSpec); int width; int height; //計算文字範圍 calcTextBounds(); if (widthMode == MeasureSpec.EXACTLY) { width = widthSize; } else { width = mTextBounds.width(); if (mCompoundDrawables != null) { if (mCompoundDrawables[TOP] != null) { width = Math.max(width,mDrawableTopBounds.width()); } if (mCompoundDrawables[BOTTOM] != null) { width = Math.max(width,mDrawableBottomBounds.width()); } //加上左右內邊距及drawable寬度和drawable間距 width += getCompoundPaddingLeft() + getCompoundPaddingRight(); width = Math.max(width,getSuggestedMinimumWidth()); if (widthMode == MeasureSpec.AT_MOST) { width = Math.min(widthSize,width); } } } if (heightMode == MeasureSpec.EXACTLY) { height = heightSize; } else { height = mTextBounds.height(); if (mCompoundDrawables != null) { if (mCompoundDrawables[LEFT] != null) { height = Math.max(height,mDrawableLeftBounds.height()); } if (mCompoundDrawables[RIGHT] != null) { height = Math.max(height,mDrawableRightBounds.height()); } //加上上下內邊距及drawable高度和drawable間距 height += getCompoundPaddingTop() + getCompoundPaddingBottom(); height = Math.max(height,getSuggestedMinimumHeight()); if (heightMode == MeasureSpec.AT_MOST) { height = Math.min(heightSize,height); } } } setMeasuredDimension(width,height); } public int getCompoundPaddingTop() { if (mCompoundDrawables == null || mCompoundDrawables[TOP] == null) { return getPaddingTop(); } else { Rect rect = new Rect(); mCompoundDrawables[TOP].copyBounds(rect); return getPaddingTop() + mDrawablePadding + rect.height(); } } public int getCompoundPaddingBottom() { if (mCompoundDrawables == null || mCompoundDrawables[BOTTOM] == null) { return getPaddingBottom(); } else { Rect rect = new Rect(); mCompoundDrawables[BOTTOM].copyBounds(rect); return getPaddingBottom() + mDrawablePadding + rect.height(); } } public int getCompoundPaddingLeft() { if (mCompoundDrawables == null || mCompoundDrawables[LEFT] == null) { return getPaddingLeft(); } else { Rect rect = new Rect(); mCompoundDrawables[LEFT].copyBounds(rect); return getPaddingLeft() + mDrawablePadding + rect.width(); } } public int getCompoundPaddingRight() { if (mCompoundDrawables == null || mCompoundDrawables[RIGHT] == null) { return getPaddingRight(); } else { Rect rect = new Rect(); mCompoundDrawables[RIGHT].copyBounds(rect); return getPaddingRight() + mDrawablePadding + rect.width(); } } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); int vspace = getBottom() - getTop() - getCompoundPaddingBottom() - getCompoundPaddingTop(); //剩餘垂直可繪製文字空間大小 int hspace = getRight() - getLeft() - getCompoundPaddingRight() - getCompoundPaddingLeft(); //剩餘水平可繪製文字空間大小 if (mCompoundDrawables != null) { if (mCompoundDrawables[LEFT] != null) { canvas.save(); canvas.translate((hspace - mTextBounds.width()) / 2.0f + getPaddingLeft(),getCompoundPaddingTop() + (vspace - mDrawableLeftBounds.height()) / 2.0f); mCompoundDrawables[LEFT].draw(canvas); canvas.restore(); } if (mCompoundDrawables[RIGHT] != null) { canvas.save(); canvas.translate(getRight() - getLeft() - getPaddingRight() - (hspace - mTextBounds.width()) / 2.0f - mDrawableRightBounds.width(),getCompoundPaddingTop() + (vspace - mDrawableRightBounds.height()) / 2.0f); mCompoundDrawables[RIGHT].draw(canvas); canvas.restore(); } if (mCompoundDrawables[TOP] != null) { canvas.save(); canvas.translate(getCompoundPaddingLeft() + (hspace - mDrawableTopBounds.width()) / 2.0f,(vspace - mTextBounds.height()) / 2.0f + getPaddingTop()); mCompoundDrawables[TOP].draw(canvas); canvas.restore(); } if (mCompoundDrawables[BOTTOM] != null) { canvas.save(); canvas.translate(getCompoundPaddingLeft() + (hspace - mDrawableBottomBounds.width()) / 2.0f,getBottom() - getTop() - getPaddingBottom() - (vspace - mTextBounds.height()) / 2.0f - mDrawableBottomBounds.height()); mCompoundDrawables[BOTTOM].draw(canvas); canvas.restore(); } } if (!TextUtils.isEmpty(mText)) { float startX = (hspace - mTextBounds.width()) / 2.0f + getCompoundPaddingLeft(); //因為drawText以baseline為基準,因此需要向下移ascent float startY = (vspace - mTextBounds.height()) / 2.0f + getCompoundPaddingTop() - mTextPaint.getFontMetrics().ascent; mTextPaint.setColor(mTextColor.getColorForState(getDrawableState(),0)); canvas.drawText(mText,mText.length(),startX,startY,mTextPaint); } } @Override protected void drawableStateChanged() { super.drawableStateChanged(); if (mTextColor != null && mTextColor.isStateful()) { mTextPaint.setColor(mTextColor.getColorForState(getDrawableState(),0)); } if (mCompoundDrawables != null) { final int[] state = getDrawableState(); for (Drawable dr : mCompoundDrawables) { if (dr != null && dr.isStateful() && dr.setState(state)) { invalidateDrawable(dr); } } } } public void setCompoundDrawablesWithIntrinsicBounds(@Nullable Drawable left,@Nullable Drawable top,@Nullable Drawable right,@Nullable Drawable bottom) { if (left != null) { left.setBounds(0,left.getIntrinsicWidth(),left.getIntrinsicHeight()); } if (right != null) { right.setBounds(0,right.getIntrinsicWidth(),right.getIntrinsicHeight()); } if (top != null) { top.setBounds(0,top.getIntrinsicWidth(),top.getIntrinsicHeight()); } if (bottom != null) { bottom.setBounds(0,bottom.getIntrinsicWidth(),bottom.getIntrinsicHeight()); } setCompoundDrawables(left,top,right,bottom); } public void setCompoundDrawables(@Nullable Drawable left,@Nullable Drawable bottom) { if (mCompoundDrawables == null) { mCompoundDrawables = new Drawable[4]; } else { if (mCompoundDrawables[LEFT] != null && mCompoundDrawables[LEFT] != left) { mCompoundDrawables[LEFT].setCallback(null); } if (mCompoundDrawables[TOP] != null && mCompoundDrawables[TOP] != top) { mCompoundDrawables[TOP].setCallback(null); } if (mCompoundDrawables[RIGHT] != null && mCompoundDrawables[RIGHT] != right) { mCompoundDrawables[RIGHT].setCallback(null); } if (mCompoundDrawables[BOTTOM] != null && mCompoundDrawables[BOTTOM] != bottom) { mCompoundDrawables[BOTTOM].setCallback(null); } } if (left != null) { mDrawableLeftBounds = new Rect(); left.copyBounds(mDrawableLeftBounds); left.setCallback(this); mCompoundDrawables[LEFT] = left; } else { mCompoundDrawables[LEFT] = null; } if (top != null) { mDrawableTopBounds = new Rect(); top.copyBounds(mDrawableTopBounds); top.setCallback(this); mCompoundDrawables[TOP] = top; } else { mCompoundDrawables[TOP] = null; } if (right != null) { mDrawableRightBounds = new Rect(); right.copyBounds(mDrawableRightBounds); right.setCallback(this); mCompoundDrawables[RIGHT] = right; } else { mCompoundDrawables[RIGHT] = null; } if (bottom != null) { mDrawableBottomBounds = new Rect(); bottom.copyBounds(mDrawableBottomBounds); bottom.setCallback(this); mCompoundDrawables[BOTTOM] = bottom; } else { mCompoundDrawables[BOTTOM] = null; } invalidate(); requestLayout(); } public void setText(CharSequence text) { this.mText = text; invalidate(); requestLayout(); } public void setTextSize(float textSize) { this.mTextSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,textSize,getResources().getDisplayMetrics()); invalidate(); requestLayout(); } public void setTextColor(@ColorInt int textColor) { this.mTextColor = ColorStateList.valueOf(textColor); invalidate(); } public void setTypeface(@Nullable Typeface tf) { if (mTextPaint.getTypeface() != tf) { mTextPaint.setTypeface(tf); requestLayout(); invalidate(); } } private void calcTextBounds() { mTextBounds = new Rect(); if (TextUtils.isEmpty(mText)) return; if (Build.VERSION.SDK_INT > Build.VERSION_CODES.Q) { mTextPaint.getTextBounds(mText,mTextBounds); } else { int width = (int) Math.ceil(mTextPaint.measureText(mText.toString())); Paint.FontMetrics fontMetrics = mTextPaint.getFontMetrics(); int height = (int) Math.ceil(fontMetrics.descent - fontMetrics.ascent); mTextBounds.set(0,width,height); } } }
感謝大家的支援,如有錯誤請指正。
以上就是本文的全部內容,希望對大家的學習有所幫助,也希望大家多多支援我們。