使用BitmapShader實現簡單繪圖
阿新 • • 發佈：2019-02-15
MainActivity中的程式碼：
package com.example.drawbitmap; import android.app.Activity; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.BitmapShader; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.LinearGradient; import android.graphics.Paint; import android.graphics.Bitmap.Config; import android.graphics.Paint.Style; import android.graphics.Shader; import android.graphics.Shader.TileMode; import android.graphics.Typeface; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; import android.widget.ImageView; public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); ImageView iv = (ImageView) this.findViewById(R.id.iv); Bitmap bitmap = createBitmap(); Canvas canvas = new Canvas(bitmap); Paint paint = new Paint(); //設定繪製文字的時候，文字大小 paint.setTextSize(50); paint.setStyle(Style.FILL); paint.setStrokeWidth(30); /* * 使用純色填充的時候，setColor設定要填充的顏色 * 如果想使用漸變色，需要使用Shader * 如果設定了shader，則使用shader * */ Bitmap icon = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher); /** * 引數1： bitmapshader要使用的圖片 * 引數2： x填充型別 * 引數3： y方向填充型別 */ Shader shader = new BitmapShader(icon, TileMode.REPEAT, TileMode.MIRROR); paint.setShader(shader); // new LinearGradient(0, 0, 100, 0, Color.BLUE, Color.RED, TileMode.REPEAT) //設定繪製顏色 paint.setColor(0xffff0000);//如果純色填充的時候，使用的顏色 //用純色填充畫布 canvas.drawColor(0xFFAAAAAA); canvas.drawText("hehehe", 100, 100, paint); canvas.drawRect(50, 50, 350, 150, paint); iv.setImageBitmap(bitmap); canvas.drawLine(0, 0, 400, 400, paint); } private Bitmap createBitmap() { Bitmap bitmap = Bitmap.createBitmap(400, 400, Config.ARGB_8888); return bitmap; } }
SecondActivity中程式碼：(作為啟動介面)
package com.example.drawbitmap; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import android.app.Activity; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.Bitmap.CompressFormat; import android.graphics.Bitmap.Config; import android.graphics.BitmapFactory; import android.graphics.BitmapShader; import android.graphics.Canvas; import android.graphics.Paint; import android.graphics.Point; import android.graphics.Shader.TileMode; import android.net.Uri; import android.net.Uri.Builder; import android.os.Bundle; import android.os.Environment; import android.util.Log; import android.view.MotionEvent; import android.view.View; import android.view.View.OnTouchListener; import android.widget.ImageView; import android.widget.Toast; public class SecondActivity extends Activity{ private Canvas canvas; private Paint paint; private ImageView iv; private Bitmap bitmap; private BitmapShader shader; public static final int BG_COLOR = 0xffaaaaaa; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); this.setContentView(R.layout.activity_main); iv = (ImageView) this.findViewById(R.id.iv); bitmap = createBitmap(); Bitmap b = BitmapFactory.decodeResource(getResources(), R.drawable.start); shader = new BitmapShader(b, TileMode.REPEAT, TileMode.REPEAT); canvas = new Canvas(bitmap); paint = new Paint(); canvas.drawColor(BG_COLOR); iv.setImageBitmap(bitmap); iv.setOnTouchListener(touchListener); } OnTouchListener touchListener = new OnTouchListener() { float startX = 0;//用來緩衝起始位置x float startY = 0;//用來緩衝起始位置y @Override public boolean onTouch(View v, MotionEvent event) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN: startX = event.getX(); startY = event.getY(); break; case MotionEvent.ACTION_MOVE: float stopX = event.getX(); float stopY = event.getY(); canvas.drawLine(startX, startY, stopX, stopY, paint); iv.setImageBitmap(bitmap); //這次的終止位置作為下次的起始位置儲存 startX = stopX; startY = stopY; break; case MotionEvent.ACTION_UP: break; default: break; } return true; } }; private Bitmap createBitmap() { Bitmap bitmap = Bitmap.createBitmap(400, 400, Config.ARGB_8888); return bitmap; } public void red(View view) { paint.setColor(0xffff0000); } public void green(View view) { paint.setColor(0xff00ff00); } public void blue(View view) { paint.setColor(0xff0000ff); } public void erase(View view) { paint.setShader(null); paint.setColor(BG_COLOR); } public void big(View view) { paint.setStrokeWidth(paint.getStrokeWidth() + 3); } public void small(View view) { float width = paint.getStrokeWidth() - 3; if(width < 1) { width = 1; } paint.setStrokeWidth(width); } public void installShader(View view) { //設定shader paint.setShader(shader); } public void uninstallShader(View view) { //取消shader paint.setShader(null); } public void save(View view) { String dirName = Environment.getExternalStorageDirectory() + "/我的大作/"; new File(dirName).mkdirs(); File file = new File(dirName,System.currentTimeMillis()+".jpg"); FileOutputStream outputStream = null; try { outputStream = new FileOutputStream(file); bitmap.compress(CompressFormat.JPEG, 75, outputStream); Toast.makeText(this, "圖片儲存到了: " + file.getAbsolutePath() , Toast.LENGTH_LONG).show(); Log.e("", file.getAbsolutePath()); Intent i = new Intent(); i.setAction(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);//設定通知系統掃描sd卡上檔案的action //這個廣播需要攜帶一個檔案的資料 // Uri uri = Uri.parse("file://" + file.getAbsolutePath());//手動拼接uri的路徑 Uri uri = Uri.fromFile(file);//呼叫api，把一個file檔案生成uri i.setData(uri); sendBroadcast(i); } catch (FileNotFoundException e) { e.printStackTrace(); }finally{ if(outputStream != null) { try { outputStream.close(); } catch (IOException e) { e.printStackTrace(); } } } //把記憶體裡的內容壓縮到一個輸出流裡 } }
在layout中作為顯示的xml：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context="com.example.drawbitmap.MainActivity" > <ImageView android:id="@+id/iv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/hello_world" /> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" > <Button android:layout_height="wrap_content" android:text="紅色" android:onClick="red" android:textColor="#ff0000" style="@style/btn_paint" /> <Button android:layout_height="wrap_content" style="@style/btn_paint" android:text="綠色" android:onClick="green" android:textColor="#00ff00" /> <Button android:layout_height="wrap_content" style="@style/btn_paint" android:text="藍色" android:textColor="#0000ff" android:onClick="blue" /> <Button android:layout_height="wrap_content" style="@style/btn_paint" android:text="擦除" android:onClick="erase" /> </LinearLayout> <RelativeLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" > <Button android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="變粗" android:onClick="big" android:layout_marginLeft="20dp" /> <Button android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="變細" android:onClick="small" android:layout_centerHorizontal="true" /> </RelativeLayout> <RelativeLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" > <Button android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="使用shader" android:onClick="installShader" android:layout_marginLeft="20dp" /> <Button android:layout_height="wrap_content" android:layout_width="wrap_content" android:text="取消shader" android:onClick="uninstallShader" android:layout_alignParentRight="true" android:layout_marginRight="20dp" /> </RelativeLayout> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="儲存" android:onClick="save" android:layout_gravity="center_horizontal" /> </LinearLayout>
配置清單檔案：(Sdcard卡讀寫權，與設定SecondActivity做為啟動介面)
<!-- 配置應用對SD卡的讀寫權 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
</activity>
<activity android:name="com.example.drawbitmap.SecondActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>