Android 圖片填充動畫

原創

丶Veer

2020-02-20 16:35

前言

最近在項目中，開發下拉刷新列表時，要做一個動畫，下拉的時候慢慢填充一個動畫，做到一個滿血復活的效果（設計師的解釋，你懂得--），然後自己寫了一個自定義的動畫實現此效果。

代碼

package com.example.loading.myloading;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

/**
 * 描述
 * Created by fww
 * date 16/4/25.
 */
public class LoadingView extends View {
    private Bitmap bitmap;
    private Paint paint1;
    private Paint paint2;
    private Paint paint3;
    private Canvas canvas;
    private  int h;
    public LoadingView(Context context) {
        this(context, null);
    }

    public LoadingView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public LoadingView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        paint1 = new Paint();
        paint1.setColor(Color.RED);
        paint2 = new Paint();
        paint2.setColor(Color.GRAY);
        paint3 = new Paint();
        paint3.setColor(Color.WHITE);
        Bitmap bitmap1 = BitmapFactory.decodeResource(context.getResources(), R.drawable.loading_0000);
        bitmap = bitmap1.extractAlpha();// 獲取一個透明圖片
        h = bitmap.getHeight();//初始化y軸座標
    }
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
    {
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);
        int width;
        int height ;
        if (widthMode == MeasureSpec.EXACTLY)
        {
            width = widthSize;
        } else
        {
            float textWidth = bitmap.getWidth();
            int desired = (int) (getPaddingLeft() + textWidth + getPaddingRight());
            width = desired;
        }

        if (heightMode == MeasureSpec.EXACTLY)
        {
            height = heightSize;
        } else
        {
            float textHeight = bitmap.getHeight();
            int desired = (int) (getPaddingTop() + textHeight + getPaddingBottom());
            height = desired;
        }
        setMeasuredDimension(width, height);
    }

    @Override
    protected void onDraw(Canvas canvas)
    {
        this.canvas = canvas;
        canvas.drawColor(Color.WHITE); // 畫布顏色
        canvas.drawBitmap(bitmap, 0, 0, paint2); //畫一個灰的圖片
        canvas.save();
        //按y來裁剪區域
        canvas.clipRect(0, h +0, bitmap.getWidth()+0,
                bitmap.getHeight()+0);
        canvas.drawBitmap(bitmap, 0, 0, paint1);
        canvas.restore();
    }
    public void updateView(int i){
        h =i;
       postInvalidate();

    }
}

MainActivity

package com.example.loading.myloading;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;

public class MainActivity extends AppCompatActivity {
    private LinearLayout mView;
    private LoadingView loadingView;
    private Button mBtn;
    private  int height;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mView = (LinearLayout) findViewById(R.id.view);
        loadingView = (LoadingView) findViewById(R.id.loadingview);
        mBtn = (Button) findViewById(R.id.but);
        Bitmap bitmap = BitmapFactory.decodeResource(this.getResources(), R.drawable.loading_0000);
        height = bitmap.getHeight();
        mBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                height= height-2;
                if(height>0){
                    loadingView.updateView(height);
                }
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

下面有開發的Demo 環境爲AndroidStudio