Package limn.backend.lwjgl.transfer

Class WindowsClipboard

java.lang.Object

limn.backend.lwjgl.transfer.WindowsClipboard

All Implemented Interfaces:

NativeClipboard

public final class WindowsClipboard
extends Object
implements NativeClipboard

The Windows clipboard, through a message-only window of our own.

Everything this process offers is rendered on demand: the formats are announced with no data, and WM_RENDERFORMAT asks for one when a program pastes. The window's messages arrive on the UI thread, inside GLFW's poll, so no thread of ours is involved in offering. A read is the other way round: any thread may open the clipboard, and the copy out of it is made on a short-lived one, so that a large picture is decoded off the UI thread.

What this process still owns when it closes is rendered then, as every Windows program does, so that what the user copied outlives the application.

A picture is offered twice, as the PNG format, which keeps its transparency, and as CF_DIB, which every program reads. It is read from PNG where there is one.

Constructor Summary

Constructors

Constructor	Description
WindowsClipboard()	UI thread.

Method Summary

Modifier and Type	Method	Description
void	close()	Lets go of the system's resources.
boolean	isOwner()
List<String>	madeAhead(List<String> offered)	The types worth making ahead of anybody asking, because this system asks on the UI thread and waits there: the picture's, where making it is slow.
void	offer(List<String> types, Function<String,byte[]> bytes)	Makes this process the clipboard's owner.
CompletableFuture<byte[]>	read(String type)	Asks for the bytes of one type.
void	setChangeListener(Runnable listener)
List<String>	types()	The types on the clipboard as the system last reported them, without asking it again.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

WindowsClipboard

public WindowsClipboard()

UI thread.

Throws:

RuntimeException - when the window cannot be made; the caller then keeps GLFW's text clipboard

Method Details

isOwner

public boolean isOwner()

Specified by:

isOwner in interface NativeClipboard

Returns:

whether what the clipboard holds was put there by the last NativeClipboard.offer(java.util.List<java.lang.String>, java.util.function.Function<java.lang.String, byte[]>) of this process and has not been replaced since

types

public List<String> types()

Description copied from interface: NativeClipboard

The types on the clipboard as the system last reported them, without asking it again.

Specified by:

types in interface NativeClipboard

Returns:

canonical type names, best first; empty when the clipboard is empty or unknown

read

public CompletableFuture<byte[]> read(String type)

Description copied from interface: NativeClipboard

Asks for the bytes of one type.

Specified by:

read in interface NativeClipboard

Parameters:

type - one of NativeClipboard.types()

Returns:

the bytes, completed on whatever thread the implementation reads on; completed exceptionally when the type is not, or no longer, there

offer

public void offer(List<String> types,
 Function<String,byte[]> bytes)

Description copied from interface: NativeClipboard

Makes this process the clipboard's owner.

Specified by:

offer in interface NativeClipboard

Parameters:

types - what is offered, best first; empty empties the clipboard

bytes - the bytes of one of those types, asked for when a program wants them; it may be called on any thread and may block, and answers null for what it cannot make

madeAhead

public List<String> madeAhead(List<String> offered)

Description copied from interface: NativeClipboard

The types worth making ahead of anybody asking, because this system asks on the UI thread and waits there: the picture's, where making it is slow.

Specified by:

madeAhead in interface NativeClipboard

Parameters:

offered - the types about to be offered

Returns:

those of offered, and of the private types this clipboard asks for itself, that should be made in the background as soon as they are offered

setChangeListener

public void setChangeListener(Runnable listener)

Specified by:

setChangeListener in interface NativeClipboard

Parameters:

listener - called, on any thread, after the clipboard's types or its owner change, an NativeClipboard.offer(java.util.List<java.lang.String>, java.util.function.Function<java.lang.String, byte[]>) of this process included; replaces the one before

close

public void close()

Description copied from interface: NativeClipboard

Lets go of the system's resources. The clipboard is not used afterwards.

Specified by:

close in interface NativeClipboard