CanvasItem

Inherits: Node < Object

Inherited By: Control, Node2D

Base class of anything 2D.

Description

Base class of anything 2D. Canvas items are laid out in a tree; children inherit and extend their parent’s transform. CanvasItem is extended by Control for anything GUI-related, and by Node2D for anything related to the 2D engine.

Any CanvasItem can draw. For this, update must be called, then NOTIFICATION_DRAW will be received on idle time to request redraw. Because of this, canvas items don’t need to be redrawn on every frame, improving the performance significantly. Several functions for drawing on the CanvasItem are provided (see draw_* functions). However, they can only be used inside the Object._notification, signal or _draw virtual functions.

Canvas items are drawn in tree order. By default, children are on top of their parents so a root CanvasItem will be drawn behind everything. This behavior can be changed on a per-item basis.

A CanvasItem can also be hidden, which will also hide its children. It provides many ways to change parameters such as modulation (for itself and its children) and self modulation (only for itself), as well as its blend mode.

Ultimately, a transform notification can be requested, which will notify the node that its global position changed in case the parent tree changed.

Note: Unless otherwise specified, all methods that have angle parameters must have angles specified as radians. To convert degrees to radians, use @GDScript.deg2rad.

Tutorials

• Viewport(视口)和画布变换
• 2D中的自定义绘图
• https://godotengine.org/asset-library/asset/528

Properties

Methods

Signals

• draw ( )

Emitted when the CanvasItem must redraw. This can only be connected realtime, as deferred will not allow drawing.

• hide ( )

Emitted when becoming hidden.

• item_rect_changed ( )

Emitted when the item’s Rect2 boundaries (position or size) have changed, or when an action is taking place that may have impacted these boundaries (e.g. changing Sprite.texture).

• visibility_changed ( )

Emitted when the visibility (hidden/visible) changes.

Enumerations

enum BlendMode:

• BLEND_MODE_MIX = 0 —- Mix blending mode. Colors are assumed to be independent of the alpha (opacity) value.
• BLEND_MODE_ADD = 1 —- Additive blending mode.
• BLEND_MODE_SUB = 2 —- Subtractive blending mode.
• BLEND_MODE_MUL = 3 —- Multiplicative blending mode.
• BLEND_MODE_PREMULT_ALPHA = 4 —- Mix blending mode. Colors are assumed to be premultiplied by the alpha (opacity) value.
• BLEND_MODE_DISABLED = 5 —- Disables blending mode. Colors including alpha are written as-is. Only applicable for render targets with a transparent background. No lighting will be applied.

Constants

• NOTIFICATION_TRANSFORM_CHANGED = 2000 —- The CanvasItem‘s transform has changed. This notification is only received if enabled by set_notify_transform or set_notify_local_transform.
• NOTIFICATION_DRAW = 30 —- The CanvasItem is requested to draw.
• NOTIFICATION_VISIBILITY_CHANGED = 31 —- The CanvasItem‘s visibility has changed.
• NOTIFICATION_ENTER_CANVAS = 32 —- The CanvasItem has entered the canvas.
• NOTIFICATION_EXIT_CANVAS = 33 —- The CanvasItem has exited the canvas.

Property Descriptions

• int light_mask

The rendering layers in which this CanvasItem responds to Light2D nodes.

• Material material

The material applied to textures on this CanvasItem.

• Color modulate

The color applied to textures on this CanvasItem.

• Color self_modulate

The color applied to textures on this CanvasItem. This is not inherited by children CanvasItems.

• bool show_behind_parent

If true, the object draws behind its parent.

• bool show_on_top

If true, the object draws on top of its parent.

• bool use_parent_material

If true, the parent CanvasItem‘s material property is used as this one’s material.

• bool visible

If true, this CanvasItem is drawn. The node is only visible if all of its antecedents are visible as well (in other words, is_visible_in_tree must return true).

Note: For controls that inherit Popup, the correct way to make them visible is to call one of the multiple popup*() functions instead.

Method Descriptions

• void _draw ( ) virtual

Overridable function called by the engine (if defined) to draw the canvas item.

• void draw_arc ( Vector2 center, float radius, float start_angle, float end_angle, int point_count, Color color, float width=1.0, bool antialiased=false )

Draws an arc between the given angles. The larger the value of point_count, the smoother the curve.

• float draw_char ( Font font, Vector2 position, String char, String next, Color modulate=Color( 1, 1, 1, 1 ) )

Draws a string character using a custom font. Returns the advance, depending on the character width and kerning with an optional next character.

• void draw_circle ( Vector2 position, float radius, Color color )

Draws a colored circle.

• void draw_colored_polygon ( PoolVector2Array points, Color color, PoolVector2Array uvs=PoolVector2Array( ), Texture texture=null, Texture normal_map=null, bool antialiased=false )

Draws a colored polygon of any amount of points, convex or concave.

• void draw_line ( Vector2 from, Vector2 to, Color color, float width=1.0, bool antialiased=false )

Draws a line from a 2D point to another, with a given color and width. It can be optionally antialiased.

• void draw_mesh ( Mesh mesh, Texture texture, Texture normal_map=null, Transform2D transform=Transform2D( 1, 0, 0, 1, 0, 0 ), Color modulate=Color( 1, 1, 1, 1 ) )

Draws a Mesh in 2D, using the provided texture. See MeshInstance2D for related documentation.

• void draw_multiline ( PoolVector2Array points, Color color, float width=1.0, bool antialiased=false )

Draws multiple, parallel lines with a uniform color.

Note: width and antialiased are currently not implemented and have no effect.

• void draw_multiline_colors ( PoolVector2Array points, PoolColorArray colors, float width=1.0, bool antialiased=false )

Draws multiple, parallel lines with a uniform width and segment-by-segment coloring. Colors assigned to line segments match by index between points and colors.

Note: width and antialiased are currently not implemented and have no effect.

• void draw_multimesh ( MultiMesh multimesh, Texture texture, Texture normal_map=null )

Draws a MultiMesh in 2D with the provided texture. See MultiMeshInstance2D for related documentation.

• void draw_polygon ( PoolVector2Array points, PoolColorArray colors, PoolVector2Array uvs=PoolVector2Array( ), Texture texture=null, Texture normal_map=null, bool antialiased=false )

Draws a polygon of any amount of points, convex or concave.

• void draw_polyline ( PoolVector2Array points, Color color, float width=1.0, bool antialiased=false )

Draws interconnected line segments with a uniform color and width and optional antialiasing.

• void draw_polyline_colors ( PoolVector2Array points, PoolColorArray colors, float width=1.0, bool antialiased=false )

Draws interconnected line segments with a uniform width, segment-by-segment coloring, and optional antialiasing. Colors assigned to line segments match by index between points and colors.

• void draw_primitive ( PoolVector2Array points, PoolColorArray colors, PoolVector2Array uvs, Texture texture=null, float width=1.0, Texture normal_map=null )

Draws a custom primitive. 1 point for a point, 2 points for a line, 3 points for a triangle and 4 points for a quad.

• void draw_rect ( Rect2 rect, Color color, bool filled=true, float width=1.0, bool antialiased=false )

Draws a rectangle. If filled is true, the rectangle will be filled with the color specified. If filled is false, the rectangle will be drawn as a stroke with the color and width specified. If antialiased is true, the lines will be antialiased.

Note: width and antialiased are only effective if filled is false.

• void draw_set_transform ( Vector2 position, float rotation, Vector2 scale )

Sets a custom transform for drawing via components. Anything drawn afterwards will be transformed by this.

• void draw_set_transform_matrix ( Transform2D xform )

Sets a custom transform for drawing via matrix. Anything drawn afterwards will be transformed by this.

• void draw_string ( Font font, Vector2 position, String text, Color modulate=Color( 1, 1, 1, 1 ), int clip_w=-1 )

Draws text using the specified font at the position (top-left corner). The text will have its color multiplied by modulate. If clip_w is greater than or equal to 0, the text will be clipped if it exceeds the specified width.

Example using the default project font:

# If using this method in a script that redraws constantly, move the
# `default_font` declaration to a member variable assigned in `_ready()`
# so the Control is only created once.
var default_font = Control.new().get_font("font")
draw_string(default_font, Vector2(64, 64), "Hello world")

See also Font.draw.

• void draw_style_box ( StyleBox style_box, Rect2 rect )

Draws a styled rectangle.

• void draw_texture ( Texture texture, Vector2 position, Color modulate=Color( 1, 1, 1, 1 ), Texture normal_map=null )

Draws a texture at a given position.

• void draw_texture_rect ( Texture texture, Rect2 rect, bool tile, Color modulate=Color( 1, 1, 1, 1 ), bool transpose=false, Texture normal_map=null )

Draws a textured rectangle at a given position, optionally modulated by a color. If transpose is true, the texture will have its X and Y coordinates swapped.

• void draw_texture_rect_region ( Texture texture, Rect2 rect, Rect2 src_rect, Color modulate=Color( 1, 1, 1, 1 ), bool transpose=false, Texture normal_map=null, bool clip_uv=true )

Draws a textured rectangle region at a given position, optionally modulated by a color. If transpose is true, the texture will have its X and Y coordinates swapped.

• void force_update_transform ( )

Forces the transform to update. Transform changes in physics are not instant for performance reasons. Transforms are accumulated and then set. Use this if you need an up-to-date transform when doing physics operations.

• RID get_canvas ( ) const

Returns the RID of the World2D canvas where this item is in.

• RID get_canvas_item ( ) const

Returns the canvas item RID used by VisualServer for this item.

• Transform2D get_canvas_transform ( ) const

Returns the transform matrix of this item’s canvas.

• Vector2 get_global_mouse_position ( ) const

Returns the global position of the mouse.

• Transform2D get_global_transform ( ) const

Returns the global transform matrix of this item.

• Transform2D get_global_transform_with_canvas ( ) const

Returns the global transform matrix of this item in relation to the canvas.

• Vector2 get_local_mouse_position ( ) const

Returns the mouse position relative to this item’s position.

• Transform2D get_transform ( ) const

Returns the transform matrix of this item.

• Rect2 get_viewport_rect ( ) const

Returns the viewport’s boundaries as a Rect2.

• Transform2D get_viewport_transform ( ) const

Returns this item’s transform in relation to the viewport.

• World2D get_world_2d ( ) const

Returns the World2D where this item is in.

• void hide ( )

Hide the CanvasItem if it’s currently visible.

• bool is_local_transform_notification_enabled ( ) const

Returns true if local transform notifications are communicated to children.

• bool is_set_as_toplevel ( ) const

Returns true if the node is set as top-level. See set_as_toplevel.

• bool is_transform_notification_enabled ( ) const

Returns true if global transform notifications are communicated to children.

• bool is_visible_in_tree ( ) const

Returns true if the node is present in the SceneTree, its visible property is true and all its antecedents are also visible. If any antecedent is hidden, this node will not be visible in the scene tree.

• Vector2 make_canvas_position_local ( Vector2 screen_point ) const

Assigns screen_point as this node’s new local transform.

• InputEvent make_input_local ( InputEvent event ) const

Transformations issued by event‘s inputs are applied in local space instead of global space.

• void set_as_toplevel ( bool enable )

If enable is true, the node won’t inherit its transform from parent canvas items.

• void set_notify_local_transform ( bool enable )

If enable is true, children will be updated with local transform data.

• void set_notify_transform ( bool enable )

If enable is true, children will be updated with global transform data.

• void show ( )

Show the CanvasItem if it’s currently hidden. For controls that inherit Popup, the correct way to make them visible is to call one of the multiple popup*() functions instead.

• void update ( )

Queue the CanvasItem for update. NOTIFICATION_DRAW will be called on idle time to request redraw.