如何解决QR code一代画布错误

问题描述

我想按照这个网站的，只有一个错误最多拍摄画布不能解析到一个变量

I am trying to execute the QR Code tutorial according to this website http://www.onbarcode.com/products/android_barcode/barcodes/qrcode.html, where only one error shoots up "canvas cannot be resolved to a variable

下面是Java code

Here is the Java code

    package com.qrcode;

    import com.onbarcode.barcode.android.AndroidColor;
    import com.onbarcode.barcode.android.IBarcode;
    import com.onbarcode.barcode.android.QRCode;
    import android.app.Activity;
    import android.graphics.Canvas;
    import android.graphics.RectF;
    import android.os.Bundle;

    public class QrcodeActivity extends Activity {


/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    QRCode barcode = new QRCode();

    /*
       QRCode Valid data char set:
            numeric data (digits 0 - 9);
            alphanumeric data (digits 0 - 9; upper case letters A -Z; nine other characters: space, $ % * + - . / : );
            byte data (default: ISO/IEC 8859-1);
            Kanji characters
    */
    barcode.setData("http://www.onbarcode.com");
    barcode.setDataMode(QRCode.M_AUTO);
    barcode.setVersion(10);
    barcode.setEcl(QRCode.ECL_M);

    //  if you want to encode GS1 compatible QR Code, you need set FNC1 mode to IBarcode.FNC1_ENABLE
    barcode.setFnc1Mode(IBarcode.FNC1_NONE);

    //  Set the processTilde property to true, if you want use the tilde character "~" to
    //  specify special characters in the input data. Default is false.
    //  1-byte character: ~ddd (character value from 0 ~ 255)
    //  ASCII (with EXT): from ~000 to ~255
    //  2-byte character: ~6ddddd (character value from 0 ~ 65535)
    //  Unicode: from ~600000 to ~665535
    //  ECI: from ~7000000 to ~7999999
    //  SJIS: from ~9ddddd (Shift JIS 0x8140 ~ 0x9FFC and 0xE040 ~ 0xEBBF)
    barcode.setProcessTilde(false);

    // unit of measure for X, Y, LeftMargin, RightMargin, TopMargin, BottomMargin
    barcode.setUom(IBarcode.UOM_PIXEL);
    // barcode module width in pixel
    barcode.setX(3f);

    barcode.setLeftMargin(15f);
    barcode.setRightMargin(15f);
    barcode.setTopMargin(15f);
    barcode.setBottomMargin(15f);
    // barcode image resolution in dpi
    barcode.setResolution(72);

    // barcode bar color and background color in Android device
    barcode.setForeColor(AndroidColor.black);
    barcode.setBackColor(AndroidColor.white);

    /*
    specify your barcode drawing area
        */
        RectF bounds = new RectF(30, 30, 0, 0);
    ************************ERROR Shoots up in the below line stating "canvas cannot be resolved into a variable***************
    barcode.drawBarcode(canvas, bounds);

}

    }

下面是我的main.xml

Here is my main.xml

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical" >


    </LinearLayout>

我在QR一代天真，所以请帮助我的code的朋友，其余

Am a naive in qr generation, so please help me with the rest of the code friends

推荐答案

您应该写的所有code以上，在Android的自定义视图的方法的onDraw。创建一个扩展 android.view.View 类的类，然后写你的code在里面。这种方法会给你一个变量是你想要的画布。看到下面的code：

You should write all of the code above, in onDraw method of a custom view in android. create a class that extends android.view.View class, and then write your code in it. this method will give you a variable that is the canvas you want. see the code below:

public class Test extends View {

public Test(Context context) {
    super(context);
}

@Override
protected void onDraw(Canvas canvas) {
    //write your code here!
}

创建该类之后，把这个观点在活动的XML文件是这样的：

after creating this class, put this view in your activity xml file like this:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

            <somepackage.somepackage.someview
                    android:layout_width="fill_parent"
                    android:layout_height="fill_parent"
            </somepackage.somepackage.someview>
</LinearLayout>

请注意：你最近创建的视图类的包替换 somepackage.somepackage ，并更换someview与您的自定义视图类名称

note: replace the somepackage.somepackage with package of your recently created view class, and replace someview with you custom view class name.

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