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Script Library: 1223 scripts
Documentation for: rebgui-image.r
Usage document for %rebgui-image.r
1. Introduction to %rebgui-image.r
rebgui-image.r is an introduction to the ease of gui creation with RebGUI, highlighting one widget, image.
2. rebgui-image At a Glance
No setup is required, just do it.
>> do %rebgui-image.r
The above image was created running REBOL/View 18.104.22.168.2, RebGUI build #93, GNU/Linux 4.0, KDE Desktop.
3. Using %rebgui-image.r
Requires REBOL/View, access to a cached copy of RebGUI or internet access for getting a cached copy.
3.1. Running %rebgui-image.r
From the library with:
>> do http://www.rebol.org/cgi-bin/cgiwrap/rebol/download-a-script.r?script-name=rebgui-image.ror locally with:
>> do %rebgui-image.r
4. What you can learn
This script is an introduction to the display function and image widget of RebGUI.
RebGUI gui building is easy, and offers a flexible 'business polish' to application design. There are many features under the hood.
This example uses the REBOL/View do-thru feature. do-thru will execute a script from the REBOL/View sandbox (another name for cache). It will retrieve the code from the internet, only if there is not a cached copy.
REBOL keeps the root directory of the sandbox in view-root. After you have downloaded RebGUI once, you can use
If you do develop something with RebGUI, and build it using the REBOL/SDK, you may not have access to do-thru. The RebGUI home site explains all this. This is just an example, and assumes you are using a full fledged REBOL/View.
Another way of getting RebGUI is clicking the REBOL/View viewtop Demo RebGUI icon.
4.2. The image widget
This short example highlights the ease of using the image widget in RebGUI. Being a short example, it does no real justice to the full power of image and RebGUI widgets.
When running, you can hover over the image for a tooltip, or click the image to execute an action block, which closes the window.
RebGUI has support for tooltips on all widgets. The widgets actually come with tooltips that you can use while developing with RebGUI.
Once rebgui.r is loaded, you have access to an examine function. This helper utility will display the details about a widget.
>> examine image USAGE: image %logo.png image logo image logo effect [crop 10x10 50x50] DESCRIPTION: An image. ATTRIBUTES: size -1x-1 effect fit options block! init function!Very handy indeed.
A quick note about the image default size -1x-1. RebGUI can be completely liquid in terms of resizing windows and smooth, reasonable placement of widgets. In this case, image defaults to -1 by -1 units, or in RebGUI speak...figure out a reasonable size when rendered...in the context of the widgets around the image and other concerns.
Another quick note. RebGUI doesn't really count things in 'pixels', it counts in 'units'. Very powerful. It allows the function request-ui to give the power of many aspects of the user interface to the user. More on this in the %rebgui-sizing.r example script.
The standard REBOL event handler is used by RebGUI. do-events is used to start the event handling loop in REBOL. The REBOL/View view function includes a call to this event loop. RebGUI requires it to be called separately, a feature that allows for processing between and around the GUI layout, the display and handling the events.
4.3. What you can change.
For early experiments with your local copy, try using other images. You don't have to, but you can also specify sizes. You could change the tip, or maybe the action block. For the next example, how about an effect with a size and an exploratory action.
image 50x12 logo.gif effect [fit gradmul green blue] tip "Click to print face details" [help face]
When clicked, something like this is produced on the console window
>> do %rebgui-image.r Script: "RebGUI image Example" (4-Jun-2007) FACE is an object of value: type word! image offset pair! 16x16 size pair! 200x48 span none! none pane none! none text none! none color none! none image image! size: 100x24 effect block! length: 4 data none! none edge none! none font none! none para none! none feel object! [redraw detect over engage] saved-area none! none rate none! none show? logic! true options block! length: 0 parent-face object! [type offset size span pane text color image effec... old-offset pair! 16x16 old-size pair! 200x48 line-list none! none changes none! none face-flags integer! 1 action object! [on-alt-click on-away on-click on-dbl-click on-edi... rebind none! none init none! none tip string! "Click will print face details"
5. What can break
You will need access to the internet, at least the first time you do-thru rebgui.r.
REBOL/Core will not have the capabilities to run RebGUI, You will need to start up REBOL/View.
The RebGUI designer, Ashley Truter has taken great strides to allow the REBOL/SDK to build a RebGUI application that does not require all the REBOL/View features for a lean, mean application. Full information starts at the RebGUI Home
A note about Mr. Truter, and an apology. The u in Truter is actually ü, a diaeresis. I hold a great deal of respect for Ashley, and not getting his name proper is a something I am looking into fixing. It has to do with getting characters encoded cross-platform. When I type it in Unicode UTF-8 under GNU/Linux, it sometimes gets mungled getting to Windows. Using the ü web entity sometimes doesn't work when there is a text processor involved. Soon I'll have it figured out and this paragraph will disappear.