149 lines
9.2 KiB
Factor
Executable File
149 lines
9.2 KiB
Factor
Executable File
USING: ui.gadgets ui.gestures help.markup help.syntax
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kernel classes strings opengl.gl models math.geometry.rect ;
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IN: ui.render
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HELP: gadget
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{ $class-description "An object which displays itself on the screen and acts on user input gestures. Gadgets have the following slots:"
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{ $list
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{ { $snippet "pref-dim" } " - a cached value for " { $link pref-dim } "; do not read or write this slot directly." }
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{ { $snippet "parent" } " - the gadget containing this one, or " { $link f } " if this gadget is not part of the visible gadget hierarchy." }
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{ { $snippet "children" } " - a vector of child gadgets. Do not modify this vector directly, instead use " { $link add-gadget } ", " { $link add-gadgets } ", " { $link unparent } " or " { $link clear-gadget } "." }
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{ { $snippet "orientation" } " - an orientation specifier. This slot is used by layout gadgets." }
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{ { $snippet "layout-state" } " - stores the layout state of the gadget. Do not read or write this slot directly, instead call " { $link relayout } " and " { $link relayout-1 } " if the gadget needs to be re-laid out." }
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{ { $snippet "visible?" } " - a boolean indicating if the gadget should display and receive user input." }
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{ { $snippet "root?" } " - if set to " { $link t } ", layout changes in this gadget will not propagate to the gadget's parent." }
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{ { $snippet "clipped?" } " - a boolean indicating if clipping will be enabled when drawing this gadget's children." }
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{ { $snippet "interior" } " - an object whose class implements the " { $link draw-interior } " generic word." }
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{ { $snippet "boundary" } " - an object whose class implements the " { $link draw-boundary } " generic word." }
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{ { $snippet "model" } " - a " { $link model } " or " { $link f } "; see " { $link "ui-control-impl" } }
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}
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"Gadgets subclass the " { $link rect } " class, and thus all instances have " { $snippet "loc" } " and " { $snippet "dim" } " instances holding their location and dimensions." }
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{ $notes
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"Other classes may inherit from " { $link gadget } " in order to re-implement generic words such as " { $link draw-gadget* } " and " { $link user-input* } ", or to define gestures with " { $link set-gestures } "." } ;
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HELP: clip
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{ $var-description "The current clipping rectangle." } ;
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HELP: draw-gadget*
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{ $values { "gadget" gadget } }
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{ $contract "Draws the gadget by making OpenGL calls. The top-left corner of the gadget should be drawn at the location stored in the " { $link origin } " variable." }
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{ $notes "This word should not be called directly. To force a gadget to redraw, call " { $link relayout-1 } "." } ;
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HELP: draw-interior
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{ $values { "interior" object } { "gadget" gadget } }
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{ $contract "Draws the interior of a gadget by making OpenGL calls. The " { $link gadget-interior } " slot may be set to objects implementing this generic word." } ;
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HELP: draw-boundary
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{ $values { "boundary" object } { "gadget" gadget } }
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{ $contract "Draws the boundary of a gadget by making OpenGL calls. The " { $link gadget-boundary } " slot may be set to objects implementing this generic word." } ;
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HELP: solid
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{ $class-description "A class implementing the " { $link draw-boundary } " and " { $link draw-interior } " generic words to draw a solid outline or a solid fill, respectively. The " { $link solid-color } " slot stores a color specifier." } ;
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HELP: gradient
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{ $class-description "A class implementing the " { $link draw-interior } " generic word to draw a smoothly shaded transition between colors. The " { $link gradient-colors } " slot stores a sequence of color specifiers and the gradient is drawn in the direction given by the " { $link gadget-orientation } " slot of the gadget." } ;
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HELP: polygon
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{ $class-description "A class implementing the " { $link draw-boundary } " and " { $link draw-interior } " generic words to draw a solid outline or a solid filled polygon, respectively. Instances of " { $link polygon } " have two slots:"
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{ $list
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{ { $link polygon-color } " - a color specifier" }
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{ { $link polygon-points } " - a sequence of points" }
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}
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} ;
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HELP: <polygon>
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{ $values { "color" "a color specifier" } { "points" "a sequence of points" } }
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{ $description "Creates a new instance of " { $link polygon } "." } ;
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HELP: <polygon-gadget>
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{ $values { "color" "a color specifier" } { "points" "a sequence of points" } { "gadget" "a new " { $link gadget } } }
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{ $description "Creates a gadget which is drawn as a solid filled polygon. The gadget's size is the minimum bounding box containing all the points of the polygon." } ;
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HELP: open-font
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{ $values { "font" "a font specifier" } { "open-font" object } }
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{ $description "Loads a font if it has not already been loaded, otherwise outputs the existing font." }
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{ $errors "Throws an error if the font does not exist." } ;
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HELP: string-width
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{ $values { "open-font" "a value output by " { $link open-font } } { "string" string } { "w" "a positive integer" } }
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{ $description "Outputs the width of a string." } ;
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HELP: text-dim
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{ $values { "open-font" "a value output by " { $link open-font } } { "text" "a string or an array of strings" } { "dim" "a pair of integers" } }
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{ $description "Outputs the dimensions of a piece of text, which is either a single-line string or an array of lines." } ;
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HELP: draw-string
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{ $values { "font" "a font specifier" } { "string" string } { "loc" "a pair of integers" } }
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{ $description "Draws a line of text." } ;
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HELP: draw-text
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{ $values { "font" "a font specifier" } { "text" "a string or an array of strings" } { "loc" "a pair of integers" } }
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{ $description "Draws text. Text is either a single-line string or an array of lines." } ;
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ARTICLE: "gadgets-polygons" "Polygon gadgets"
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"A polygon gadget renders a simple shaded polygon."
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{ $subsection <polygon-gadget> }
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"Some pre-made polygons:"
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{ $subsection arrow-up }
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{ $subsection arrow-right }
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{ $subsection arrow-down }
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{ $subsection arrow-left }
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{ $subsection close-box }
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"Polygon gadgets are rendered by the " { $link polygon } " pen protocol implementation." ;
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ARTICLE: "ui-paint" "Customizing gadget appearance"
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"The UI carries out the following steps when drawing a gadget:"
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{ $list
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{ "The " { $link draw-interior } " generic word is called on the value of the " { $link gadget-interior } " slot." }
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{ "The " { $link draw-gadget* } " generic word is called on the gadget." }
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{ "The gadget's visible children are drawn, determined by calling " { $link visible-children } " on the gadget." }
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{ "The " { $link draw-boundary } " generic word is called on the value of the " { $link gadget-boundary } " slot." }
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}
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"Now, each one of these steps will be covered in detail."
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{ $subsection "ui-pen-protocol" }
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{ $subsection "ui-paint-custom" } ;
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ARTICLE: "ui-pen-protocol" "UI pen protocol"
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"The " { $link gadget-interior } " and " { $link gadget-boundary } " slots of a gadget facilitate easy factoring and sharing of drawing logic. Objects stored in these slots must implement the pen protocol:"
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{ $subsection draw-interior }
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{ $subsection draw-boundary }
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"The default value of these slots is the " { $link f } " singleton, which implements the above protocol by doing nothing."
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$nl
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"Some other pre-defined implementations:"
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{ $subsection solid }
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{ $subsection gradient }
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{ $subsection polygon }
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"Custom implementations must follow the guidelines set forth in " { $link "ui-paint-custom" } "." ;
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ARTICLE: "text-rendering" "Rendering text"
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"Unlike OpenGL, Factor's FreeType binding only includes the bare essentials, and there is rarely any need to directly call words in the " { $vocab-link "freetype" } " vocabulary directly. Instead, the UI provides high-level wrappers."
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$nl
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"Font objects are never constructed directly, and instead are obtained by calling a word:"
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{ $subsection open-font }
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"Measuring text:"
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{ $subsection text-dim }
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{ $subsection text-height }
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{ $subsection text-width }
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"Rendering text:"
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{ $subsection draw-string }
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{ $subsection draw-text } ;
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ARTICLE: "ui-paint-custom" "Implementing custom drawing logic"
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"The UI uses OpenGL to render gadgets. Custom rendering logic can be plugged in with the " { $link "ui-pen-protocol" } ", or by implementing a generic word:"
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{ $subsection draw-gadget* }
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"Custom drawing code has access to the full OpenGL API in the " { $vocab-link "opengl" } " vocabulary."
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$nl
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"The UI uses a co-ordinate system where the y axis is oriented down. The OpenGL " { $link GL_MODELVIEW } " matrix is not saved or restored when rendering a gadget. Instead, the origin of the gadget relative to the OpenGL context is stored in a variable:"
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{ $subsection origin }
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"Custom drawing implementations can translate co-ordinates manually, or save and restore the " { $link GL_MODELVIEW } " matrix."
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$nl
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"OpenGL state must not be altered as a result of drawing a gadget, so any flags which were enabled should be disabled, and vice versa."
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$nl
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"Gadgets must not draw outside of their bounding box, however clipping is not enforced by default, for performance reasons. This can be changed by setting the " { $link gadget-clipped? } " slot to " { $link t } " in the gadget's constructor."
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$nl
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"Saving the " { $link GL_MODELVIEW } " matrix and enabling/disabling flags can be done in a clean way using the combinators documented in the following section."
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{ $subsection "gl-utilities" }
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{ $subsection "text-rendering" } ;
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ABOUT: "ui-paint-custom"
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