Android画布Canvas绘制drawBitmap基于源Rect和目的Rect，Kotlin

你的名字 2024-02-05 12:27 46阅读 0赞

### Android画布Canvas绘制drawBitmap基于源Rect和目的Rect，Kotlin ###

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![849160ac0c894395b9d1c08245857791.png][]

<?xml version="1.0" encoding="utf-8"?>
    <androidx.appcompat.widget.LinearLayoutCompat xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/darker_gray"
        android:orientation="vertical"
        app:divider="@android:drawable/divider_horizontal_bright"
        app:dividerPadding="5dp"
        app:showDividers="beginning|middle|end">
    
        <ImageView
            android:id="@+id/iv"
            android:layout_width="300px"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:background="@drawable/ic_launcher_background"
            android:scaleType="fitCenter"
            android:src="@mipmap/pic" />
    
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">
    
            <ImageView
                android:id="@+id/iv1"
                android:layout_width="300px"
                android:layout_height="wrap_content"
                android:layout_margin="10dp"
                android:background="@drawable/ic_launcher_background" />
    
            <ImageView
                android:id="@+id/iv2"
                android:layout_width="300px"
                android:layout_height="wrap_content"
                android:layout_margin="10dp"
                android:background="@drawable/ic_launcher_background" />
    
            <ImageView
                android:id="@+id/iv3"
                android:layout_width="300px"
                android:layout_height="wrap_content"
                android:layout_margin="10dp"
                android:background="@drawable/ic_launcher_background" />
    
        </LinearLayout>
    
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">
    
            <ImageView
                android:id="@+id/iv4"
                android:layout_width="300px"
                android:layout_height="wrap_content"
                android:layout_margin="10dp"
                android:background="@drawable/ic_launcher_background" />
    
            <ImageView
                android:id="@+id/iv5"
                android:layout_width="300px"
                android:layout_height="wrap_content"
                android:layout_margin="10dp"
                android:background="@drawable/ic_launcher_background" />
    
            <ImageView
                android:id="@+id/iv6"
                android:layout_width="300px"
                android:layout_height="wrap_content"
                android:layout_margin="10dp"
                android:background="@drawable/ic_launcher_background" />
    
        </LinearLayout>
    </androidx.appcompat.widget.LinearLayoutCompat>

import android.graphics.Bitmap
    import android.graphics.Canvas
    import android.graphics.Color
    import android.graphics.Rect
    import android.graphics.drawable.BitmapDrawable
    import androidx.appcompat.app.AppCompatActivity
    import android.os.Bundle
    import android.widget.ImageView
    import androidx.lifecycle.lifecycleScope
    import kotlinx.coroutines.Dispatchers
    import kotlinx.coroutines.delay
    import kotlinx.coroutines.launch
    
    class MainActivity : AppCompatActivity() {
        private var iv: ImageView? = null
        private var iv1: ImageView? = null
        private var iv2: ImageView? = null
        private var iv3: ImageView? = null
        private var iv4: ImageView? = null
        private var iv5: ImageView? = null
        private var iv6: ImageView? = null
    
        override fun onCreate(savedInstanceState: Bundle?) {
            super.onCreate(savedInstanceState)
            setContentView(R.layout.activity_main)
    
            iv = findViewById(R.id.iv)
            iv1 = findViewById(R.id.iv1)
            iv2 = findViewById(R.id.iv2)
            iv3 = findViewById(R.id.iv3)
            iv4 = findViewById(R.id.iv4)
            iv5 = findViewById(R.id.iv5)
            iv6 = findViewById(R.id.iv6)
    
            lifecycleScope.launch(Dispatchers.Main) {
                delay(500)
    
                capture1()
                capture2()
                capture3()
                capture4()
                capture5()
                capture6()
            }
        }
    
        private fun capture1() {
            val srcBmp = (iv!!.drawable as BitmapDrawable).bitmap
    
            //创建一个和srcBmp宽高相同背景为Color.LTGRAY空Bitmap
            val bitmap = Bitmap.createBitmap(srcBmp!!.width, srcBmp!!.height, Bitmap.Config.ARGB_8888);
            val canvas = Canvas(bitmap)
            canvas.drawColor(Color.LTGRAY)
    
            val dstW = srcBmp!!.width / 4
            val dstH = srcBmp!!.height / 2
            val dstRect = Rect(0, 0, dstW, dstH) //bitmap坐标
            canvas.drawBitmap(
                srcBmp,
                null,
                dstRect,
                null
            )
    
            iv1!!.setImageBitmap(bitmap)
        }
    
        private fun capture2() {
            val srcBmp = (iv!!.drawable as BitmapDrawable).bitmap
    
            val bitmap = Bitmap.createBitmap(srcBmp!!.width, srcBmp!!.height, Bitmap.Config.ARGB_8888)
            val canvas = Canvas(bitmap)
            canvas.drawColor(Color.GREEN)
    
            //复制一个宽1/2和高1/2的原图。
            val dstW = srcBmp!!.width / 2
            val dstH = srcBmp!!.height / 2
    
            //框住原图中心点右下1/4部分。
            val srcRect = Rect(dstW, dstH, srcBmp!!.width, srcBmp!!.height)
    
            //bitmap左上角偏移20开始摆放。
            val dstRect = Rect(20, 20, dstW + 20, dstH + 20)
            canvas.drawBitmap(
                srcBmp,
                srcRect,
                dstRect,
                null
            )
    
            iv2!!.setImageBitmap(bitmap)
        }
    
        private fun capture3() {
            val srcBmp = (iv!!.drawable as BitmapDrawable).bitmap
    
            val bitmap = Bitmap.createBitmap(srcBmp!!.width, srcBmp!!.height, Bitmap.Config.ARGB_8888)
            val canvas = Canvas(bitmap)
            canvas.drawColor(Color.CYAN)
    
            val dstW = srcBmp!!.width / 2
            val dstH = srcBmp!!.height / 2
    
            val centerX = srcBmp!!.width / 2
            val centerY = srcBmp!!.height / 2
    
            //框住原图右上1/4部分，坐标仍以原图为准。
            val srcRect = Rect(centerX, 0, centerX + srcBmp!!.width / 2, centerY)
    
            //摆放到bitmap的中心位置。
            val dstRect = Rect(centerX - dstW / 2, centerY - dstH / 2, centerX + dstW / 2, centerY + dstH / 2)
    
            canvas.drawBitmap(
                srcBmp,
                srcRect,
                dstRect,
                null
            )
    
            iv3!!.setImageBitmap(bitmap)
        }
    
        private fun capture4() {
            val srcBmp = (iv!!.drawable as BitmapDrawable).bitmap
    
            val w = srcBmp!!.width / 2
            val h = srcBmp!!.height / 2
    
            val bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888)
            val canvas = Canvas(bitmap)
            canvas.drawColor(Color.YELLOW)
    
            val centerX = srcBmp!!.width / 2
            val centerY = srcBmp!!.height / 2
    
            //框住原图中心1/2部分，坐标仍以原图为准。
            val srcRect = Rect(centerX - w / 2, centerY - h / 2, centerX + w / 2, centerY + h / 2)
    
            //直接摆放到bitmap。
            val dstRect = Rect(0, 0, w, h)
    
            canvas.drawBitmap(
                srcBmp,
                srcRect,
                dstRect,
                null
            )
    
            iv4!!.setImageBitmap(bitmap)
        }
    
        //截取原图右下1/3的部分
        private fun capture5() {
            val srcBmp = (iv!!.drawable as BitmapDrawable).bitmap
    
            val w = srcBmp!!.width / 3
            val h = srcBmp!!.height / 3
    
            val bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888)
            val canvas = Canvas(bitmap)
            canvas.drawColor(Color.RED)
    
            val left = (srcBmp!!.width / 3) * 2
            val top = (srcBmp!!.height / 3) * 2
    
            //框住原图右下1/3部分，坐标仍以原图为准
            val srcRect = Rect(left, top, left + w, top + h)
    
            //直接摆放到bitmap。
            val dstRect = Rect(0, 0, w, h)
    
            canvas.drawBitmap(
                srcBmp,
                srcRect,
                dstRect,
                null
            )
    
            iv5!!.setImageBitmap(bitmap)
        }
    
        //截取原图左侧中间1/3部分
        private fun capture6() {
            val srcBmp = (iv!!.drawable as BitmapDrawable).bitmap
    
            val w = srcBmp!!.width / 3
            val h = srcBmp!!.height / 3
    
            val bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888)
            val canvas = Canvas(bitmap)
            canvas.drawColor(Color.BLUE)
    
            val top = srcBmp!!.height / 3
    
            //框住原图部分。
            val srcRect = Rect(0, top, 0 + w, top + h)
    
            //直接摆放到bitmap。
            val dstRect = Rect(0, 0, w, h)
    
            canvas.drawBitmap(
                srcBmp,
                srcRect,
                dstRect,
                null
            )
    
            iv6!!.setImageBitmap(bitmap)
        }
    }

[Android Drawable 转化成 Bitmap-CSDN博客文章浏览阅读1.8k次。/\*Java代码 将Drawable转化为Bitmap \*/ Bitmap drawableToBitmap(Drawable drawable) \{ int width = drawable.getIntrinsicWidth(); int height = drawable.getIntrinsicHeight(); Bitmap bitmap![favicon32.ico][]https://blog.csdn.net/zhangphil/article/details/43767535][Android Drawable _ Bitmap-CSDN_1.8k_Java_ _Drawable_Bitmap _ Bitmap drawableToBitmap_Drawable drawable_ _ int width _ drawable.getIntrinsicWidth_ int height _ drawable.getIntrinsicHeight_ Bitmap bitmap_favicon32.ico_https_blog.csdn.net_zhangphil_article_details_43767535]

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[849160ac0c894395b9d1c08245857791.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/05/0b2518220b3048dea9e1b65bbc14bb93.png
[favicon32.ico]: https://image.dandelioncloud.cn/pgy_files/images/2024/02/05/441d0ef5d38a4782bb4c2d537b51f1f7.png
[Android Drawable _ Bitmap-CSDN_1.8k_Java_ _Drawable_Bitmap _ Bitmap drawableToBitmap_Drawable drawable_ _ int width _ drawable.getIntrinsicWidth_ int height _ drawable.getIntrinsicHeight_ Bitmap bitmap_favicon32.ico_https_blog.csdn.net_zhangphil_article_details_43767535]: https://blog.csdn.net/zhangphil/article/details/43767535
[Android Material Design _LinearLayoutCompat_divider_linearlayout _-CSDN_9.6k_Android Material Design _LinearLayoutCompat_dividerAndroid Material Design _LinearLayoutCompat_LinearLayout_View_divider_1_app_showDividers_beg_linearlayout _favicon32.ico_https_blog.csdn.net_zhangphil_article_details_48899585]: https://blog.csdn.net/zhangphil/article/details/48899585