有些App在點擊下載按鈕的時候，可以在按鈕上顯示進度，我們可以通過繼承原生Button，重寫onDraw來實現帶進度條的按鈕。
Github：https://github.com/imcloudfloating/ProgressBar
1.效果：
2.原理：
創建三個GradientDrawable作為按鈕背景、進度條背景和進度條前景，通過計算進度條的百分比來設置寬度，然后調用invalidate()重繪。GradientDrawable設置顏色、圓角等參數，當然你也可以直接加載xml作為背景。
3.自定義參數：
在values目錄建一個attrs.xml文件
<?xml version="." encoding="utf-"?> <resources> <attr name="progressColor" format="color" /> <attr name="progressBackColor" format="color" /> <attr name="progress" format="integer" /> <attr name="minProgress" format="integer" /> <attr name="maxProgress" format="integer" /> <declare-styleable name="ProgressButton"> <attr name="progressColor" /> <attr name="progressBackColor" /> <attr name="buttonColor" format="color" /> <attr name="cornerRadius" format="dimension" /> <attr name="progress" /> <attr name="minProgress" /> <attr name="maxProgress" /> <attr name="progressMargin" format="dimension" /> </declare-styleable> </resources>
3.按鈕類：
在setProgress方法中改變mProgress的值，然后調用invalidate()重繪，因為我這里定義了一個minProgress(默認為0)，所以在計算進度條寬度的時候，當前進度和最大進度都要先減去minProgress再做除法。
if (progressWidth < mCornerRadius * 2) { progressWidth = mCornerRadius * 2;} 當進度條寬度小于2倍圓角半徑的時候，進度條的圓角就和背景的圓角不一致，所以加上了上面這段代碼。
獲取寬度和高度其實用getWidth()和getHeight()也可以，只不過在設計器中沒法看到效果，所以我用了getMeasuredWidth()和getMeasuredHeight()。
package com.cloud.customviews; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.drawable.GradientDrawable; import android.support.v.widget.AppCompatButton; import android.util.AttributeSet; public class ProgressButton extends AppCompatButton { private float mCornerRadius = ; private float mProgressMargin = ; private boolean mFinish; private int mProgress; private int mMaxProgress = ; private int mMinProgress = ; private GradientDrawable mDrawableButton; private GradientDrawable mDrawableProgressBackground; private GradientDrawable mDrawableProgress; public ProgressButton(Context context, AttributeSet attrs) { super(context, attrs); initialize(context, attrs); } public ProgressButton(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); initialize(context, attrs); } private void initialize(Context context, AttributeSet attrs) { //Progress background drawable mDrawableProgressBackground = new GradientDrawable(); //Progress drawable mDrawableProgress = new GradientDrawable(); //Normal drawable mDrawableButton = new GradientDrawable(); //Get default normal color int defaultButtonColor = getResources().getColor(R.color.colorGray, null); //Get default progress color int defaultProgressColor = getResources().getColor(R.color.colorGreen, null); //Get default progress background color int defaultBackColor = getResources().getColor(R.color.colorGray, null); TypedArray attr = context.obtainStyledAttributes(attrs, R.styleable.ProgressButton); try { mProgressMargin = attr.getDimension(R.styleable.ProgressButton_progressMargin, mProgressMargin); mCornerRadius = attr.getDimension(R.styleable.ProgressButton_cornerRadius, mCornerRadius); //Get custom normal color int buttonColor = attr.getColor(R.styleable.ProgressButton_buttonColor, defaultButtonColor); //Set normal color mDrawableButton.setColor(buttonColor); //Get custom progress background color int progressBackColor = attr.getColor(R.styleable.ProgressButton_progressBackColor, defaultBackColor); //Set progress background drawable color mDrawableProgressBackground.setColor(progressBackColor); //Get custom progress color int progressColor = attr.getColor(R.styleable.ProgressButton_progressColor, defaultProgressColor); //Set progress drawable color mDrawableProgress.setColor(progressColor); //Get default progress mProgress = attr.getInteger(R.styleable.ProgressButton_progress, mProgress); //Get minimum progress mMinProgress = attr.getInteger(R.styleable.ProgressButton_minProgress, mMinProgress); //Get maximize progress mMaxProgress = attr.getInteger(R.styleable.ProgressButton_maxProgress, mMaxProgress); } finally { attr.recycle(); } //Set corner radius mDrawableButton.setCornerRadius(mCornerRadius); mDrawableProgressBackground.setCornerRadius(mCornerRadius); mDrawableProgress.setCornerRadius(mCornerRadius - mProgressMargin); setBackgroundDrawable(mDrawableButton); mFinish = false; } @Override protected void onDraw(Canvas canvas) { if (mProgress > mMinProgress && mProgress <= mMaxProgress && !mFinish) { //Calculate the width of progress float progressWidth = (float) getMeasuredWidth() * ((float) (mProgress - mMinProgress) / mMaxProgress - mMinProgress); //If progress width less than x corner radius, the radius of progress will be wrong if (progressWidth < mCornerRadius * ) { progressWidth = mCornerRadius * ; } //Set rect of progress mDrawableProgress.setBounds((int) mProgressMargin, (int) mProgressMargin, (int) (progressWidth - mProgressMargin), getMeasuredHeight() - (int) mProgressMargin); //Draw progress mDrawableProgress.draw(canvas); if (mProgress == mMaxProgress) { setBackgroundDrawable(mDrawableButton); mFinish = true; } } super.onDraw(canvas); } /** * Set current progress */ public void setProgress(int progress) { if (!mFinish) { mProgress = progress; setBackgroundDrawable(mDrawableProgressBackground); invalidate(); } } public void setMaxProgress(int maxProgress) { mMaxProgress = maxProgress; } public void setMinProgress(int minProgress) { mMinProgress = minProgress; } public void reset() { mFinish = false; mProgress = mMinProgress; } }使用：
<com.cloud.customviews.ProgressButton android:id="@+id/button_progress_green" android:layout_width="dp" android:layout_height="wrap_content" android:layout_marginTop="dp" android:textAllCaps="false" android:textColor="@color/colorWhite" android:text="@string/button_progress" app:cornerRadius="dp" app:progressMargin="dp" app:progressColor="@color/colorGreen" app:buttonColor="@color/colorGreen" />
總結
以上所述是小編給大家介紹的Android 進度條按鈕ProgressButton的實現代碼，希望對大家有所幫助，如果大家有任何疑問歡迎給我留言小編會及時回復大家的！
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