Kbase 13788: How resolution + system font affect images and other widgets
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
10/05/1998 |
|
How resolution + system font affect images and other widgets
UNDERSTANDING HOW RESOLUTION AND THE SYSTEM FONT AFFECT
WIDGETS AND IMAGES
SYSTEM FONT AND HOW IT AFFECTS WIDGET SIZES
PPU is Progress Portable Unit (for ease in understanding,
consider a unit as a character but Actually it is a
character with vertical decoration needed to draw it as a
fill-in. That is, it is the HEIGHT of a FILL-IN, but the
WIDTH of an character in that font.).
If you are using a small font for the system font then
there are, for example, 7 pixels for the width of a unit
(char) and 26 pixels for the height of a unit(char). Please
note that these numbers are for example only. To determine
how many pixels are being used at your current system font,
display session:pixels-per-row and session:pixels-per-column.
If you are using a large font for the system font then
there are,for example, 9 pixels for the width of a unit
(char) and 29 pixels for the height of a unit (char).
(Again this is only an example).
Given this information, if you were to define a button in
character units and run it with a small system font then
there will be less pixels used and therefore it will be
smaller than if you used a large font.
Generally bitmaps are a fixed size. A common size is 32 x
32 pixels. For example, if you use a 32 x 32 bitmap and
then you create a button that is defined in character units
that the image fits nicely into with a small font it may
look fine. But if you then run it with a large font, you
will find that more pixels are used per unit (char)
therefore your button will be bigger (but your image
will stay the same size leaving whitespace in your button).
1)To avoid this, it is recommended that you define your
button also in pixelsso that it will match your image in
size. Now if you compile and run in large or small font it
will make no difference in terms of your image not fitting
your button. You will still only use a certain number of
pixels. Your whole button (all widgets) may be larger or
smaller and you may want to tweak the layout at runtime to
make sure widgets look good in relation to a position of
another.
2)Another solution is to avoid bitmaps (or convert to .ico)
and use icons(.ico files). They have a clear background
that take on the background color of the widget it resides
in. So for instance, if your image no long fits nicely in
your button you will not see a weird gap of a different
color but will see just your image in the button. Then you
can just adjust the coordinates at which the image is
displayed in the button so that it is centered. This can
be done after the button has been realized.
3)You may want to have a different bitmap for smallfont or
largefont.
Often when you change resolution, a new system font is
introduced too. Sometimes the layout of your screen will
not be exactly what you want. You can also make runtime
adjustments based on the session:pixels-per-row and the
session:pixels-per-column if you no longer like the way
your screen layout looks with a new system font. This is
what Progress does when you run under different
resolutions/system fonts.
RESOLUTION
Resolution is used in this case as the number of pixels
that are used to build your entire display area (screen). In
other words, if you use a resolution of 800 by 600 then
your display software is using 800 pixels across the width
of your screen and 600 pixels down one column of your screen
(height). If you were to change to a higher resolution say
1024 x 760 then you are cramming a lot more pixels into the
makeup of your screen therefore the size of a pixel is
smaller.
Now given this definition of resolution and using the above
example where you have a button and an image that were
defined in pixels, then you will find that by going to a
higher resolution from a lower one, you will end up using
the same amount of pixels but they will be much smaller so
your image and button will both shrink in size. They will
still fit together well however without any gaps. This is
how to avoid problems going from one resolution to another.
COMPILED CODE
Up until now, I have addressed the case where you are
developing code and compiling it with different system
fonts/resolutions. Running COMPILED code (rcode) on a system
with a different font may still produce problems.
Currently, when you compile and save the rcode with a
particular system font, the PPU size is saved in the rcode
(even if you originally defined the widget in pixels).
Therefore, if you run it on a system with a different system
font, you will still have the same problems as if you had
defined the button/widget in characters. In the above
example, for instance, the button may change size but the
image does not and you are left with whitespace.
If this is the case then you must use option 2 or 3 to get
around this.
Progress Software Technical Support Note # 13788