Calling DrawPath2 with Filled=True on certain polygon paths throws ArrayIndexOutOfBoundsException from inside DrawWuLine. The bug is deterministic — the attached minimal project reproduces it 100%
Minimal repro code (full project attached):
The polygon is a small octagon (~13×15 px) with all vertices safely inside the BC bounds. I'm pretty sure the error also will happen for other polygons as well. In the app I'm developing, polygons are randomly fabricated and the ArrayIndexOutOfBoundsException happened quite often. BitmapCreator is version 4.73
I have done following investigations:
-Substitutting BitmapCreator library with BitmapCreator.bas and BCPath.bas found in BitmapCreator Source.zip in this post.
-Logs shows the error occurs on line: 871 in BitmapCreator.bas
-In line 864 of BitmapCreator the CheckBounds is false, so it is no checking for bounds
-CheckBounds originates from the sub ShouldCheckBounds in BitmapCreator
I suggests to change the margins in BitmapCreator.ShouldCheckBounds from one pixel to two pixels like this:
Logs showing error message:
bc.mWidth:30, bc.mHeight:25
path x extremes: 7.29707 - 20.795
path y extremes: 9.325 - 23.8353
Error occurred on line: 55 (B4XMainPage)
java.lang.ArrayIndexOutOfBoundsException: Index 12 out of bounds for length 12
at b4j.example.bitmapcreator._drawwuline(bitmapcreator.java:3613)
at b4j.example.bitmapcreator._drawfullpath(bitmapcreator.java:2305)
at b4j.example.bitmapcreator._drawpath2(bitmapcreator.java:2450)
at b4j.example.b4xmainpage._button1_click(b4xmainpage.java:131)Minimal repro code (full project attached):
Minimal repro code ()full project attached:
Dim bc As BitmapCreator
bc.Initialize(30, 25)
Dim Path As BCPath
Path.Initialize(19.24428,14.80650)
Path.LineTo(18.92485,10.29233)
Path.LineTo(14.41068,9.88168)
Path.LineTo(8.92918,9.32500)
Path.LineTo(7.29707,14.80650)
Path.LineTo(7.38147,21.83570)
Path.LineTo(14.41068,23.83530)
Path.LineTo(20.79500,21.19083)
Path.LineTo(19.24428,14.80650)
Dim brush As BCBrush = bc.CreateBrushFromColor(xui.Color_Black)
bc.DrawPath2(Path, brush, True, 0)The polygon is a small octagon (~13×15 px) with all vertices safely inside the BC bounds. I'm pretty sure the error also will happen for other polygons as well. In the app I'm developing, polygons are randomly fabricated and the ArrayIndexOutOfBoundsException happened quite often. BitmapCreator is version 4.73
I have done following investigations:
-Substitutting BitmapCreator library with BitmapCreator.bas and BCPath.bas found in BitmapCreator Source.zip in this post.
-Logs shows the error occurs on line: 871 in BitmapCreator.bas
-In line 864 of BitmapCreator the CheckBounds is false, so it is no checking for bounds
-CheckBounds originates from the sub ShouldCheckBounds in BitmapCreator
I suggests to change the margins in BitmapCreator.ShouldCheckBounds from one pixel to two pixels like this:
Suggested change to the ShouldCheckBounds sub:
Private Sub ShouldCheckBounds(PointsX() As Float, PointsY() As Float) As Boolean
For i = 0 To PointsY.Length - 1
If PointsX(i) < 2 Or PointsX(i) >= mWidth - 2 Or PointsY(i) < 2 Or PointsY(i) >= mHeight - 2 Then
Return True
End If
Next
Return False
End Sub