Question

My problem is that, i can’t view all the image or some pixels.

I have a imageview and bitmap on it. And with canvas library, I drawing the imageview limits. But the result is wrong. Why not sample the left and lower boundaries of the image? If I increase the brush size if it is.

Image : https://i.stack.imgur.com/R3Byw.jpg

I will show only the code of this part of my app

//Init imagebitmap
largeBitmap = Bitmap.createBitmap(200,200, Bitmap.Config.ARGB_8888);

//Init canvas
canvas = new Canvas(largeBitmap);
canvas.drawColor(0xffffffff);

//Set largeBitmap on Image
as.setImageBitmap(largeBitmap);

//Init Pincel
pincel1 = new Paint();
pincel1.setARGB(255, 0, 0, 0);

//Draw Limits
int ancho = canvas.getWidth();
int alto = canvas.getHeight();

canvas.drawLine(0, 0, ancho, 0, pincel1); // Superior
canvas.drawLine(0, alto, ancho, alto, pincel1); // Inferior
canvas.drawLine(0, 0, 0, alto, pincel1); // Izq
canvas.drawLine(ancho, 0, ancho, alto, pincel1); // Drch

xml

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/sv"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_gravity="center_vertical|center_horizontal" >

    <HorizontalScrollView
        android:id="@+id/hsv"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_gravity="center_vertical|center_horizontal" >

        <LinearLayout
            android:id="@+id/ll"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_gravity="center_vertical|center_horizontal"
            android:gravity="center_vertical|center_horizontal" >

            <ImageView
                android:id="@+id/imageView1"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:contentDescription="@string/app_name"
                android:scaleType="center"
                tools:context=".SIDetailFragment" />
        </LinearLayout>
    </HorizontalScrollView>

</ScrollView>

I set scrollview only for test the bitmap image with scroll views on a easy form

Thanks in advance!

Answer 1

It’s because you’re going “too far”. As with (almost) everything in programming, canvas indexes are 0 based. So you need to use ancho -1 and alto - 1.

 canvas.drawLine(0, 0, ancho - 1, 0, pincel1); // Superior