I want to clarify the following issue...
On 10/24/2016 9:11 AM, Alexandr Scherbatiy wrote:
Using floating point scale leads that drawing the same thing from
different coordinates gives different results. For example filling a
rectangle with size (1, 1) from location (0, 0) and UI scale 1.5 gives
scaled region (0, 0, 1.5, 1.5) which is rounded to (0, 0, 2, 2). The
same rectangle filled from the location (1, 1) gives the scaled region
(1.5, 1.5, 3, 3) which is rounded to (2, 2, 3, 3). The first rectangle
has size 2 in the device space and the second one has 1.
First, while those primitives would be drawn in 2 different sizes, the
first should be 1x1 and the second should be 2x2 if they follow our fill
rules. Were you seeing something different? Still, the point you bring
up about the two being 2 different sizes is acknowledged. Fill rule
rounding for these rectangles should be "ceil(coordinate - 0.5)".
Drawn with an integer translation of 0,0 (i.e. before scrolling
operations or damage repair):
scale = 1.5
translate = 0,0 in device pixels
fillRect(0, 0, 1, 1)
transforms to 0.0, 0.0, 1.5, 1.5
fills (0,0,1,1)
covers 1x1 pixels
fillRect(1, 1, 1, 1)
transforms to 1.5, 1.5, 3.0, 3.0
fills (1,1,3,3)
covers 2x2 pixels
scale = 1.5
translate = 1,1 in device pixels
fillRect(0, 0, 1, 1)
transforms to 1.0, 1.0, 2.5, 2.5
fills (1,1,2,2)
covers 1x1 pixels
fillRect(1, 1, 1, 1)
transforms to 2.5, 2.5, 4.0, 4.0
fills (2,2,4,4)
covers 2x2 pixels
No change in the relative sizes is observed. Now, if you are talking
about an integer translation in user space, then there is a difference,
as in:
scale = 1.5
translate = 1,1 in user space
= 1.5,1.5 in device space
fillRect(0, 0, 1, 1)
transforms to 1.5, 1.5, 3.0, 3.0
fills (1,1,3,3)
covers 2x2 pixels
fillRect(1, 1, 1, 1)
transforms to 3.0, 3.0, 4.5, 4.5
fills (3,3,4,4)
covers 1x1 pixels
That can create a problem, but only if the translation is an integer
distance in user space. If RepaintManager is applying integer distances
in device space, then it should not affect the relative sizes of the
rendered primitives.
Were you seeing that happen? Because that would be a rendering bug in
fillRect...
...jim
As a result drawing a component from some coordinates and using
Graphics.copyArea() to translate an image to a new location could have a
differ results than just drawing the same component from the new location.
The fix suggests to disable the JScrollPane area copying for floating
point scales.
Thanks,
Alexandr.
On 10/7/2016 4:30 PM, Alexandr Scherbatiy wrote:
On 10/6/2016 11:42 PM, Sergey Bylokhov wrote:
Hi, Alexandr.
Can you please provide some standalone small example, which emulates
this artifacts via java2d API. (The pattern which we use in
RepainManager). It will help to understand the problem.
The code sample [1] draws two the same shapes (with different colors)
one after another into areas (x, y, w, h) and (x+w, y, w, h)
accordingly in different ways.
The shape is constructed from the following parts:
1. Fill clip area
- set clip (x, y, w, h)
- fill the whole image
As a result only clipped area is filled.
2. Fill rect
- fill rect(x, y, w, h) // big rect
- fill rect(x+1, y+1, w-2, h-2) // small rect
3. Draw center lines
- draw line (x, cy, x + w, cy)
- draw line (cx, y, cx, y + h)
The program has the following options:
RECT - draw two shapes one after another from point (0, 0)
SHIFTED_RECT - draw two shapes one after another from point (x, y)
BACKBUFFER - draw the shape into a backbuffer with size (w, h) and
draw the backbuffer from the point (x, y)
SCALED_BACKBUFFER - draw the shape into a scaled backbuffer with
size (ceil(w*scale), ceil(h*scale)) with scaled graphics from point
(0, 0) and draw it into the rectangle (x, y, w, h)
ENLARGED_SCALED_BACKBUFFER - draw the shape into a scaled backbuffer
with size (ceil((x+w)*scale), ceil((y+h)*scale)) with scaled graphics
from point (x, y) and draw it into the rectangle (0, 0, x+w, y+h)
The resulted images are placed in the directory [2].
Directory name "rect-[7,5,10,8]" means that the rectangles (7,5,10,8)
was used for the shape drawing.
Each screenshot name follows the template "
screenshot-N-[x,y,w,h]-TYPE.png" where the type is a program option
used for the image generation.
Screenshots with suffix "-compare" compares the golden image (shape
drawn in to the rectangle (x, y, w, h)) with the generated image. The
golden image is on the top left side. The generated image is shown on
the right and bottom side.
The RepaintManager has an assumption that drawing something in some
area (x, y, w, h) or just drawing the same thing into an image with
translated graphics g.translate(-x1, -y1) and drawing the image into
the area(x, y, w, h) has the the same result.
As it is shown on screenshots this statement is not true for floating
point scales.
For example the same shape drawn from the point (0,0) and (x,y) look
differently (see [3] and [4]).
The solution could be just to use an enlarged backbuffer with size
(x+w, y+h) with scaled graphics, draw the component into the rectangle
(x, y, w, h) and draw the backbuffer into the area (0,0, x+w, y+h).
Even the scaled enlarged backbuffer is used the results can be differ
(see [5] where the rectangle [7, 5, 11, 9] is used. The backbuffer is
drawn into bigger size).
[1] code samples:
http://cr.openjdk.java.net/~alexsch/8162350/code/00/Java2DFPSamples.java
[2] dir with screenshots results:
http://cr.openjdk.java.net/~alexsch/8162350/results
[3] RECT:
http://cr.openjdk.java.net/~alexsch/8162350/results/rect-%5b7%2c5%2c10%2c8%5d/screenshot-01-%5b7%2c5%2c10%2c8%5d-rects.png
[4] SHIFTED_RECT:
http://cr.openjdk.java.net/~alexsch/8162350/results/rect-%5b7%2c5%2c10%2c8%5d/screenshot-02-%5b7%2c5%2c10%2c8%5d-shifted-rects.png
[5] ENLARGED_SCALED_BACKBUFFER compare:
http://cr.openjdk.java.net/~alexsch/8162350/results/rect-%5b7%2c5%2c11%2c9%5d/screenshot-05-%5b7%2c5%2c11%2c9%5d-enlarged-scaled-backbuffers-compare.png
Thanks,
Alexandr.
On 06.10.16 20:07, Alexandr Scherbatiy wrote:
Hello,
Could you review the fix:
bug: https://bugs.openjdk.java.net/browse/JDK-8162350
webrev: http://cr.openjdk.java.net/~alexsch/8162350/webrev.00
The fix uses the solution suggest by Jim in the email:
http://mail.openjdk.java.net/pipermail/2d-dev/2016-October/007737.html
To draw to a VolatileImage backbuffer its graphics transform is
set to
identity and device coordinates are used to set the buffer clip.
Copying the backbuffer image to the graphics has some problems.
-------------
// Since there is no drawImage(img, float x, float y)...
destination.translate(pixelx1 / scaleX, pixely1 / scaleY)
destination.drawImage(img, 0, 0)
-------------
This code solves the problem for the top left corner of the region.
All Graphics.drawImage(...) methods scales the image size and it looks
like ceil(img.getWidth() * scaleX) can be differ from the
ceil(pixelx1 +
img.getWidth() * scaleX) - pixelx1 so the right bottom corner of the
image does not fit the required point.
There is also a question could a line drawn from one point and then
from another has a different width in pixels because the graphics scale
is not integer.
The proposed fix prepares a backbuffer with size [x + w, y + h] in a
user space and a component is drawn in to the region [pixelx1, pixely1,
pixely2, pixely2] in the device space.
After that the necessary clip is set to the graphics and whole image
is just drawn into it.
The new logic is used only the component graphics configuration is
scaled the graphics configuration has the same scales. So it possible
just to copy the backbuffer surface data to the graphics surface data.
For other cases like for rotated graphics transform it seems it is
necessary to have more complicated algorithm.
This solves problems with repainted region but there are still
artifacts with JInternalFrame moving or a component scrolling, This can
be related to the RepaintManager.copyArea() method which needs to be
updated in the similar way. I have created an issue on it:
JDK-8167305 RepaintManager.copyArea() method should be updated for
floating point UI scale
https://bugs.openjdk.java.net/browse/JDK-8167305
Thanks,
Alexandr.
