Module org.freedesktop.cairo

Package org.freedesktop.cairo

Class Surface

java.lang.Object

io.github.jwharm.cairobindings.Proxy

org.freedesktop.cairo.Surface

All Implemented Interfaces:

AutoCloseable

Direct Known Subclasses:

ImageSurface, PDFSurface, PSSurface, RecordingSurface, ScriptSurface, SurfaceObserver, SVGSurface, TeeSurface

public sealed class Surface
extends Proxy
implements AutoCloseable
permits ImageSurface, PDFSurface, PSSurface, RecordingSurface, SVGSurface, ScriptSurface, SurfaceObserver, TeeSurface

Base class for surfaces.

Surface is the abstract type representing all different drawing targets that cairo can render to. The actual drawings are performed using a cairo context.

A cairo surface is created by using backend-specific constructors, typically of the form of a static create() method.

Most surface types allow accessing the surface without using Cairo functions. If you do this, keep in mind that it is mandatory that you call flush() before reading from or writing to the surface and that you must use markDirty() after modifying it.

Note that for surface types other than ImageSurface it might be necessary to acquire the surface's device first. See Device.acquire() for a discussion of devices.

Constructor Summary

Constructors

Constructor	Description
Surface(MemorySegment address)	Constructor used internally to instantiate a java Surface object for a native cairo_surface_t instance

Method Summary

Modifier and Type	Method	Description
void	close()	Closing a surface will invoke finish(), which will flush the surface and drop all references to external resources.
Surface	copyPage()	Emits the current page for backends that support multiple pages, but doesn't clear it, so that the contents of the current page will be retained for the next page.
static Surface	createForRectangle(Surface target, double x, double y, double width, double height)	Create a new surface that is a rectangle within the target surface.
static <T extends Surface> T	createSimilar(T other, Content content, int width, int height)	Create a new surface that is as compatible as possible with an existing surface.
static ImageSurface	createSimilarImage(Surface other, Format format, int width, int height)	Create a new image surface that is as compatible as possible for uploading to and the use in conjunction with an existing surface.
void	destroy()	Invokes the cleanup action that is normally invoked during garbage collection.
void	finish()	This function finishes the surface and drops all references to external resources.
Surface	flush()	Do any pending drawing for the surface and also restore any temporary modifications cairo has made to the surface's state.
Content	getContent()	This function returns the content type of surface which indicates whether the surface contains color and/or alpha information.
Device	getDevice()	This function returns the device for a surface.
Point	getDeviceOffset()	This function returns the previous device offset set by setDeviceOffset(double, double).
Point	getDeviceScale()	This function returns the previous device scale set by setDeviceScale(double, double).
Point	getFallbackResolution()	This function returns the previous fallback resolution set by setFallbackResolution(double, double), or default fallback resolution if never set.
void	getFontOptions(FontOptions options)	Retrieves the default font rendering options for the surface.
byte[]	getMimeData(MimeType mimeType)	Return mime data previously attached to the surface using the specified mime type.
SurfaceType	getSurfaceType()	This function returns the type of the backend used to create a surface.
static org.gnome.glib.Type	getType()	Get the CairoSurface GType
MemorySegment	getUserData(UserDataKey key)	Return user data previously attached to the surface using the specified key.
boolean	hasShowTextGlyphs()	Returns whether the surface supports sophisticated Context.showTextGlyphs(java.lang.String, org.freedesktop.cairo.Glyphs) operations.
ImageSurface	mapToImage(RectangleInt extents)	Returns an image surface that is the most efficient mechanism for modifying the backing store of the target surface.
Surface	markDirty()	Tells cairo that drawing has been done to surface using means other than cairo, and that cairo should reread any cached areas.
Surface	markDirtyRectangle(int x, int y, int width, int height)	Like markDirty(), but drawing has been done only to the specified rectangle, so that cairo can retain cached contents for other parts of the surface.
Surface	setDeviceOffset(double xOffset, double yOffset)	Sets an offset that is added to the device coordinates determined by the CTM when drawing to surface .
Surface	setDeviceScale(double xScale, double yScale)	Sets a scale that is multiplied to the device coordinates determined by the CTM when drawing to surface .
Surface	setFallbackResolution(double xPixelsPerInch, double yPixelsPerInch)	Set the horizontal and vertical resolution for image fallbacks.
Surface	setMimeData(MimeType mimeType, byte[] data)	Attach an image in the format mimeType to the surface.
UserDataKey	setUserData(UserDataKey key, MemorySegment userData)	Attach user data to the surface.
Surface	showPage()	Emits and clears the current page for backends that support multiple pages.
Status	status()	Checks whether an error has previously occurred for this surface.
boolean	supportsMimeType(MimeType mimeType)	Return whether this surface supports mime_type.
void	unmapImage(ImageSurface image)	Unmaps the image surface as returned from mapToImage(RectangleInt).

Methods inherited from class io.github.jwharm.cairobindings.Proxy

equals, handle, hashCode

Methods inherited from class java.lang.Object

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

Constructor Details

Surface

public Surface(MemorySegment address)

Constructor used internally to instantiate a java Surface object for a native cairo_surface_t instance

Parameters:

address - the memory address of the native cairo_surface_t instance

Method Details

destroy

public void destroy()

Invokes the cleanup action that is normally invoked during garbage collection. If the instance is "owned" by the user, the destroy() function is run to dispose the native instance.

createSimilar

public static <T extends Surface> T createSimilar(T other,
 Content content,
 int width,
 int height)

Create a new surface that is as compatible as possible with an existing surface. For example the new surface will have the same device scale, fallback resolution and font options as other . Generally, the new surface will also use the same backend as other , unless that is not possible for some reason. The type of the returned surface may be examined with getSurfaceType().

Initially the surface contents are all 0 (transparent if contents have transparency, black otherwise.)

Use createSimilarImage(Surface, Format, int, int) if you need an image surface which can be painted quickly to the target surface.

Type Parameters:

T - the type of the created Surface

Parameters:

other - an existing surface used to select the backend of the new surface

content - the content for the new surface

width - width of the new surface, (in device-space units)

height - height of the new surface (in device-space units)

Returns:

the newly allocated surface.

Since:

1.0

createSimilarImage

public static ImageSurface createSimilarImage(Surface other,
 Format format,
 int width,
 int height)

Create a new image surface that is as compatible as possible for uploading to and the use in conjunction with an existing surface. However, this surface can still be used like any normal image surface. Unlike createSimilar(Surface, Content, int, int) the new image surface won't inherit the device scale from other.

Initially the surface contents are all 0 (transparent if contents have transparency, black otherwise.)

Use createSimilar(Surface, Content, int, int) if you don't need an image surface.

Parameters:

other - an existing surface used to select the preference of the new surface

format - the format for the new surface

width - width of the new surface, (in pixels)

height - height of the new surface, (in pixels)

Returns:

the newly allocated surface

Since:

1.12

createForRectangle

public static Surface createForRectangle(Surface target,
 double x,
 double y,
 double width,
 double height)

Create a new surface that is a rectangle within the target surface. All operations drawn to this surface are then clipped and translated onto the target surface. Nothing drawn via this sub-surface outside of its bounds is drawn onto the target surface, making this a useful method for passing constrained child surfaces to library routines that draw directly onto the parent surface, i.e. with no further backend allocations, double buffering or copies.

The semantics of subsurfaces have not been finalized yet unless the rectangle is in full device units, is contained within the extents of the target surface, and the target or subsurface's device transforms are not changed.

Parameters:

target - an existing surface for which the sub-surface will point to

x - the x-origin of the sub-surface from the top-left of the target surface (in device-space units)

y - the y-origin of the sub-surface from the top-left of the target surface (in device-space units)

width - width of the sub-surface (in device-space units)

height - height of the sub-surface (in device-space units)

Returns:

the newly allocated surface.

Since:

1.10

status

public Status status()

Checks whether an error has previously occurred for this surface.

Returns:

Status.SUCCESS, Status.NULL_POINTER, Status.NO_MEMORY, Status.READ_ERROR, Status.INVALID_CONTENT, Status.INVALID_FORMAT, or Status.INVALID_VISUAL.

Since:

1.0

finish

public void finish()

This function finishes the surface and drops all references to external resources. For example, for the Xlib backend it means that cairo will no longer access the drawable, which can be freed. After calling finish() the only valid operations on a surface are checking status, getting and setting user, referencing and destroying, and flushing and finishing it. Further drawing to the surface will not affect the surface but will instead trigger a Status.SURFACE_FINISHED error.

When the Surface instance is destroyed, cairo will call finish() if it hasn't been called already, before freeing the resources associated with the surface.

Since:

1.0

flush

public Surface flush()

Do any pending drawing for the surface and also restore any temporary modifications cairo has made to the surface's state. This function must be called before switching from drawing on the surface with cairo to drawing on it directly with native APIs, or accessing its memory outside of Cairo. If the surface doesn't support direct access, then this function does nothing.

Returns:

the surface

Since:

1.0

getDevice

public Device getDevice()

This function returns the device for a surface. See Device.

Returns:

The device for surface or null if the surface does not have an associated device.

Since:

1.10

getFontOptions

public void getFontOptions(FontOptions options)

Retrieves the default font rendering options for the surface. This allows display surfaces to report the correct subpixel order for rendering on them, print surfaces to disable hinting of metrics and so forth. The result can then be used with cairo_scaled_font_create().

Parameters:

options - a FontOptions object into which to store the retrieved options. All existing values are overwritten

Since:

1.0

getContent

public Content getContent()

This function returns the content type of surface which indicates whether the surface contains color and/or alpha information. See Content.

Returns:

The content type of ths surface.

Since:

1.2

markDirty

public Surface markDirty()

Tells cairo that drawing has been done to surface using means other than cairo, and that cairo should reread any cached areas. Note that you must call flush() before doing such drawing.

Returns:

the surface

Since:

1.0

markDirtyRectangle

public Surface markDirtyRectangle(int x,
 int y,
 int width,
 int height)

Like markDirty(), but drawing has been done only to the specified rectangle, so that cairo can retain cached contents for other parts of the surface.

Any cached clip set on the surface will be reset by this function, to make sure that future cairo calls have the clip set that they expect.

Parameters:

x - X coordinate of dirty rectangle

y - Y coordinate of dirty rectangle

width - width of dirty rectangle

height - height of dirty rectangle

Returns:

the surface

Since:

1.0

setDeviceOffset

public Surface setDeviceOffset(double xOffset,
 double yOffset)

Sets an offset that is added to the device coordinates determined by the CTM when drawing to surface . One use case for this function is when we want to create a cairo_surface_t that redirects drawing for a portion of an onscreen surface to an offscreen surface in a way that is completely invisible to the user of the cairo API. Setting a transformation via Context.translate(double, double) isn't sufficient to do this, since functions like Context.deviceToUser(Point) will expose the hidden offset.

Note that the offset affects drawing to the surface as well as using the surface in a source pattern.

Parameters:

xOffset - the offset in the X direction, in device units

yOffset - the offset in the Y direction, in device units

Returns:

the surface

Since:

1.0

getDeviceOffset

public Point getDeviceOffset()

This function returns the previous device offset set by setDeviceOffset(double, double).

Returns:

the x and y values of the returned Point object contain the offset in the X and Y direction, in device units

Since:

1.2

getDeviceScale

public Point getDeviceScale()

This function returns the previous device scale set by setDeviceScale(double, double).

Returns:

the x and y values of the returned Point object contain the scale in the X and Y direction, in device units

Since:

1.14

setDeviceScale

public Surface setDeviceScale(double xScale,
 double yScale)

Sets a scale that is multiplied to the device coordinates determined by the CTM when drawing to surface . One common use for this is to render to very high resolution display devices at a scale factor, so that code that assumes 1 pixel will be a certain size will still work. Setting a transformation via Context.scale(double, double) isn't sufficient to do this, since functions like Context.deviceToUser(Point) will expose the hidden scale.

Note that the scale affects drawing to the surface as well as using the surface in a source pattern.

Parameters:

xScale - a scale factor in the X direction

yScale - a scale factor in the Y direction

Returns:

the surface

Since:

1.14

setFallbackResolution

public Surface setFallbackResolution(double xPixelsPerInch,
 double yPixelsPerInch)

Set the horizontal and vertical resolution for image fallbacks.

When certain operations aren't supported natively by a backend, cairo will fallback by rendering operations to an image and then overlaying that image onto the output. For backends that are natively vector-oriented, this function can be used to set the resolution used for these image fallbacks, (larger values will result in more detailed images, but also larger file sizes).

Some examples of natively vector-oriented backends are the ps, pdf, and svg backends.

For backends that are natively raster-oriented, image fallbacks are still possible, but they are always performed at the native device resolution. So this function has no effect on those backends.

Note: The fallback resolution only takes effect at the time of completing a page (with Context.showPage() or Context.copyPage()) so there is currently no way to have more than one fallback resolution in effect on a single page.

The default fallback resolution is 300 pixels per inch in both dimensions.

Parameters:

xPixelsPerInch - horizontal setting for pixels per inch

yPixelsPerInch - vertical setting for pixels per inch

Returns:

the surface

Since:

1.2

getFallbackResolution

public Point getFallbackResolution()

This function returns the previous fallback resolution set by setFallbackResolution(double, double), or default fallback resolution if never set.

Returns:

the x and y values of the returned Point object contain the horizontal and vertical pixels per inch

Since:

1.8

getSurfaceType

public SurfaceType getSurfaceType()

This function returns the type of the backend used to create a surface. See SurfaceType for available types.

Returns:

The type of Surface.

Since:

1.2

copyPage

public Surface copyPage()

Emits the current page for backends that support multiple pages, but doesn't clear it, so that the contents of the current page will be retained for the next page. Use showPage() if you want to get an empty page after the emission.

There is a convenience function for this in Context, namely Context.copyPage().

Returns:

the surface

Since:

1.6

showPage

public Surface showPage()

Emits and clears the current page for backends that support multiple pages. Use copyPage() if you don't want to clear the page.

There is a convenience function for this that takes a Context namely Context.showPage().

Returns:

the surface

Since:

1.6

hasShowTextGlyphs

public boolean hasShowTextGlyphs()

Returns whether the surface supports sophisticated Context.showTextGlyphs(java.lang.String, org.freedesktop.cairo.Glyphs) operations. That is, whether it actually uses the provided text and cluster data to a Context.showTextGlyphs(java.lang.String, org.freedesktop.cairo.Glyphs) call.

Note: Even if this function returns false, a Context.showTextGlyphs(java.lang.String, org.freedesktop.cairo.Glyphs) operation targeted at surface will still succeed. It just will act like a Context.showGlyphs(org.freedesktop.cairo.Glyphs) operation. Users can use this function to avoid computing UTF-8 text and cluster mapping if the target surface does not use it.

Returns:

true if surface supports Context.showTextGlyphs(java.lang.String, org.freedesktop.cairo.Glyphs), false otherwise

Since:

1.8

setMimeData

public Surface setMimeData(MimeType mimeType,
 byte[] data)

Attach an image in the format mimeType to the surface. To remove the data from a surface, call this function with same mime type and null for data.

The attached image (or filename) data can later be used by backends which support it (currently: PDF, PS, SVG and Win32 Printing surfaces) to emit this data instead of making a snapshot of the surface. This approach tends to be faster and requires less memory and disk space.

The recognized MIME types are the following: MimeType.JPEG, MimeType.PNG, MimeType.JP2, MimeType.URI, MimeType.UNIQUE_ID, MimeType.JBIG2, MimeType.JBIG2_GLOBAL, MimeType.JBIG2_GLOBAL_ID, MimeType.CCITT_FAX, MimeType.CCITT_FAX_PARAMS.

See corresponding backend surface docs for details about which MIME types it can handle. Caution: the associated MIME data will be discarded if you draw on the surface afterwards. Use this function with care.

Even if a backend supports a MIME type, that does not mean cairo will always be able to use the attached MIME data. For example, if the backend does not natively support the compositing operation used to apply the MIME data to the backend. In that case, the MIME data will be ignored. Therefore, to apply an image in all cases, it is best to create an image surface which contains the decoded image data and then attach the MIME data to that. This ensures the image will always be used while still allowing the MIME data to be used whenever possible.

Language binding note: The data is passed to cairo as a memory segment backed by the on-heap region of memory that holds the given byte array. See MemorySegment.ofArray(byte[]) for more details.

Parameters:

mimeType - the MIME type of the image data

data - the image data to attach to the surface

Returns:

the surface

Since:

1.10

getMimeData

public byte[] getMimeData(MimeType mimeType)

Return mime data previously attached to the surface using the specified mime type. If no data has been attached with the given mime type, null is returned.

Language binding note: The returned mime data is a copy of the actual data attached to the surface.

Parameters:

mimeType - the mime type of the image data

Returns:

the image data to attached to the surface

Since:

1.10

supportsMimeType

public boolean supportsMimeType(MimeType mimeType)

Return whether this surface supports mime_type.

Parameters:

mimeType - the mime type

Returns:

mimeType true if this surface supports mime_type, false otherwise

Since:

1.12

mapToImage

public ImageSurface mapToImage(RectangleInt extents)

Returns an image surface that is the most efficient mechanism for modifying the backing store of the target surface. The region retrieved may be limited to the extents or null for the whole surface.

Note, the use of the original surface as a target or source whilst it is mapped is undefined. The result of mapping the surface multiple times is undefined. Calling close() destroy() or finish() on the resulting image surface results in undefined behavior. Letting the image surface get garbage-collected from Java results in undefined behavior. Changing the device transform of the image surface or of the source surface before the image surface is unmapped results in undefined behavior.

Parameters:

extents - limit the extraction to an rectangular region

Returns:

the newly allocated surface. This function always returns a valid pointer, but it will return a pointer to a "nil" surface if the original is already in an error state or any other error occurs.

Since:

1.12

unmapImage

public void unmapImage(ImageSurface image)

Unmaps the image surface as returned from mapToImage(RectangleInt).

The content of the image will be uploaded to the target surface. Afterwards, the image is destroyed.

Using an image surface which wasn't returned by mapToImage(RectangleInt) results in undefined behavior.

Parameters:

image - the currently mapped image

Since:

1.12

close

public void close()

Closing a surface will invoke finish(), which will flush the surface and drop all references to external resources. A closed surface cannot be used to perform drawing operations and cannot be reopened.

Although the Java bindings make an effort to properly dispose native resources using a Cleaner, this is not guaranteed to work in all situations. Users must therefore always call close() or finish() on surfaces (either manually or with a try-with-resources statement) or risk issues like resource exhaustion and data loss.

Specified by:

close in interface AutoCloseable

setUserData

public UserDataKey setUserData(UserDataKey key,
 MemorySegment userData)

Attach user data to the surface. To remove user data from a surface, call this function with the key that was used to set it and null for userData.

Parameters:

key - the key to attach the user data to

userData - the user data to attach to the surface

Returns:

the key

Throws:

NullPointerException - if key is null

Since:

1.4

getUserData

public MemorySegment getUserData(UserDataKey key)

Return user data previously attached to the surface using the specified key. If no user data has been attached with the given key this function returns null.

The returned memory segment has zero length. It can be resized with MemorySegment.reinterpret(long)^RESTRICTED.

Parameters:

key - the UserDataKey the user data was attached to

Returns:

the user data previously attached or null

Since:

1.4

getType

public static org.gnome.glib.Type getType()

Get the CairoSurface GType

Returns:

the GType