Hello,
I hope this question belongs in the Android Developers and not Android
Beginners group but I have a question about ScrollViews. I am
currently working with a customized GraphView class and am trying to
put it into a ScrollView but it doesn't seem to work. Whenever I run
the code, it comes up with a blank screen. I've written the code in
XML and also tried to create the ScrollView encapsulating the
GraphView programmatically but whenever the code runs, it comes up
with just a blank screen and GraphView's onDraw() is never called.
Here's the code (with XML file):
GraphView.java:
public class GraphView extends View {
private Paint paint;
private float[] values;
private String[] horlabels;
private String[] verlabels;
private String title;
public GraphView(Context context, AttributeSet attributeSet) {
super(context, attributeSet);
title = "Graph";
float[] values = new float[] { 2.0f, 1.5f, 2.5f, 1.0f,
3.0f };
String[] verlabels = new String[] { "great", "ok", "bad" };
String[] horlabels = new String[] { "today", "tomorrow",
"next week", "next month" };
if (values == null)
values = new float[0];
else
this.values = values;
if (horlabels == null)
this.horlabels = new String[0];
else
this.horlabels = horlabels;
if (verlabels == null)
this.verlabels = new String[0];
else
this.verlabels = verlabels;
paint = new Paint();
}
@Override
protected void onDraw(Canvas canvas) {
float border = 20;
float horstart = border * 2;
float height = getHeight();
float width = getWidth() - 1;
float max = getMax();
float min = getMin();
float diff = max - min;
float graphheight = height - (2 * border);
float graphwidth = width - (2 * border);
paint.setTextAlign(Align.LEFT);
int vers = verlabels.length - 1;
for (int i = 0; i < verlabels.length; i++) {
paint.setColor(Color.DKGRAY);
float y = ((graphheight / vers) * i) + border;
canvas.drawLine(horstart, y, width, y, paint);
paint.setColor(Color.WHITE);
canvas.drawText(verlabels[i], 0, y, paint);
}
int hors = horlabels.length - 1;
for (int i = 0; i < horlabels.length; i++) {
paint.setColor(Color.DKGRAY);
float x = ((graphwidth / hors) * i) + horstart;
canvas.drawLine(x, height - border, x, border, paint);
paint.setTextAlign(Align.CENTER);
if (i==horlabels.length-1)
paint.setTextAlign(Align.RIGHT);
if (i==0)
paint.setTextAlign(Align.LEFT);
paint.setColor(Color.WHITE);
canvas.drawText(horlabels[i], x, height - 4, paint);
}
paint.setTextAlign(Align.CENTER);
canvas.drawText(title, (graphwidth / 2) + horstart, border -
4, paint);
float colwidth = (width - (horstart)) / (horlabels.length -
1);
float lasth = 0;
for (int i = 0; i < values.length; i++) {
float val = values[i] - min;
float rat = val / diff;
float h = graphheight * rat;
if (i > 0)
canvas.drawLine(((i - 1) * colwidth) + horstart,
(border - lasth) + graphheight, (i * colwidth) + horstart, (border -
h) + graphheight, paint);
lasth = h;
}
}
private float getMax() {
float largest = Integer.MIN_VALUE;
for (int i = 0; i < values.length; i++)
if (values[i] > largest)
largest = values[i];
return largest;
}
private float getMin() {
float smallest = Integer.MAX_VALUE;
for (int i = 0; i < values.length; i++)
if (values[i] < smallest)
smallest = values[i];
return smallest;
}
}
Graph.java:
public class Graph extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
}
main.xml:
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android";
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<com.examples.graph.GraphView android:layout_width="fill_parent"
android:layout_height="fill_parent"
/>
</ScrollView>
Any help would be greatly appreciated! Thanks!
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