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authorPřemysl Janouch <p@janouch.name>2018-09-08 16:54:17 +0200
committerPřemysl Janouch <p@janouch.name>2018-09-08 16:54:17 +0200
commit3173202cc1e08762c6e156a8fffd23269a5ddb2b (patch)
tree95c4a06f8384d41b15e9c22afac0a387de79dc51 /nexgb/examples/create-window
parent632b3ae494d45755525644fe5d04475c95aae364 (diff)
parent3906399e7c2a40fbaf355de572cf50a314083f64 (diff)
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Merge aarzilli/xgb, branch xcb1.12 as nexgb
History has been linearized and rewritten to stay under the new subdirectory. I want to make changes incompatible to BurntSushi/xgb. The history begs for being thrown away entirely because of its quality and because it doesn't cover the Google period but it is still useful for copyright tracking.
Diffstat (limited to 'nexgb/examples/create-window')
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diff --git a/nexgb/examples/create-window/main.go b/nexgb/examples/create-window/main.go
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+// Example create-window shows how to create a window, map it, resize it,
+// and listen to structure and key events (i.e., when the window is resized
+// by the window manager, or when key presses/releases are made when the
+// window has focus). The events are printed to stdout.
+package main
+
+import (
+ "fmt"
+
+ "github.com/BurntSushi/xgb"
+ "github.com/BurntSushi/xgb/xproto"
+)
+
+func main() {
+ X, err := xgb.NewConn()
+ if err != nil {
+ fmt.Println(err)
+ return
+ }
+
+ // xproto.Setup retrieves the Setup information from the setup bytes
+ // gathered during connection.
+ setup := xproto.Setup(X)
+
+ // This is the default screen with all its associated info.
+ screen := setup.DefaultScreen(X)
+
+ // Any time a new resource (i.e., a window, pixmap, graphics context, etc.)
+ // is created, we need to generate a resource identifier.
+ // If the resource is a window, then use xproto.NewWindowId. If it's for
+ // a pixmap, then use xproto.NewPixmapId. And so on...
+ wid, _ := xproto.NewWindowId(X)
+
+ // CreateWindow takes a boatload of parameters.
+ xproto.CreateWindow(X, screen.RootDepth, wid, screen.Root,
+ 0, 0, 500, 500, 0,
+ xproto.WindowClassInputOutput, screen.RootVisual, 0, []uint32{})
+
+ // This call to ChangeWindowAttributes could be factored out and
+ // included with the above CreateWindow call, but it is left here for
+ // instructive purposes. It tells X to send us events when the 'structure'
+ // of the window is changed (i.e., when it is resized, mapped, unmapped,
+ // etc.) and when a key press or a key release has been made when the
+ // window has focus.
+ // We also set the 'BackPixel' to white so that the window isn't butt ugly.
+ xproto.ChangeWindowAttributes(X, wid,
+ xproto.CwBackPixel|xproto.CwEventMask,
+ []uint32{ // values must be in the order defined by the protocol
+ 0xffffffff,
+ xproto.EventMaskStructureNotify |
+ xproto.EventMaskKeyPress |
+ xproto.EventMaskKeyRelease})
+
+ // MapWindow makes the window we've created appear on the screen.
+ // We demonstrated the use of a 'checked' request here.
+ // A checked request is a fancy way of saying, "do error handling
+ // synchronously." Namely, if there is a problem with the MapWindow request,
+ // we'll get the error *here*. If we were to do a normal unchecked
+ // request (like the above CreateWindow and ChangeWindowAttributes
+ // requests), then we would only see the error arrive in the main event
+ // loop.
+ //
+ // Typically, checked requests are useful when you need to make sure they
+ // succeed. Since they are synchronous, they incur a round trip cost before
+ // the program can continue, but this is only going to be noticeable if
+ // you're issuing tons of requests in succession.
+ //
+ // Note that requests without replies are by default unchecked while
+ // requests *with* replies are checked by default.
+ err = xproto.MapWindowChecked(X, wid).Check()
+ if err != nil {
+ fmt.Printf("Checked Error for mapping window %d: %s\n", wid, err)
+ } else {
+ fmt.Printf("Map window %d successful!\n", wid)
+ }
+
+ // This is an example of an invalid MapWindow request and what an error
+ // looks like.
+ err = xproto.MapWindowChecked(X, 0).Check()
+ if err != nil {
+ fmt.Printf("Checked Error for mapping window 0x1: %s\n", err)
+ } else { // neva
+ fmt.Printf("Map window 0x1 successful!\n")
+ }
+
+ // Start the main event loop.
+ for {
+ // WaitForEvent either returns an event or an error and never both.
+ // If both are nil, then something went wrong and the loop should be
+ // halted.
+ //
+ // An error can only be seen here as a response to an unchecked
+ // request.
+ ev, xerr := X.WaitForEvent()
+ if ev == nil && xerr == nil {
+ fmt.Println("Both event and error are nil. Exiting...")
+ return
+ }
+
+ if ev != nil {
+ fmt.Printf("Event: %s\n", ev)
+ }
+ if xerr != nil {
+ fmt.Printf("Error: %s\n", xerr)
+ }
+ }
+}