forked from AuroraMiddleware/gtk
Allow adding constraints described through VFL
This commit is contained in:
Emmanuele Bassi
parent
5ea8167802
commit
859c95b435
@ -64,9 +64,10 @@
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#include "gtkconstraintprivate.h"
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#include "gtkconstraintexpressionprivate.h"
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#include "gtkconstraintsolverprivate.h"
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#include "gtklayoutchild.h"
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#include "gtkconstraintvflparserprivate.h"
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#include "gtkdebug.h"
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#include "gtklayoutchild.h"
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#include "gtkintl.h"
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#include "gtkprivate.h"
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#include "gtksizerequest.h"
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@ -1585,3 +1586,219 @@ gtk_constraint_layout_remove_guide (GtkConstraintLayout *layout,
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gtk_layout_manager_layout_changed (GTK_LAYOUT_MANAGER (layout));
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}
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static GtkConstraintAttribute
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attribute_from_name (const char *name)
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{
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if (name == NULL || *name == '\0')
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return GTK_CONSTRAINT_ATTRIBUTE_NONE;
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/* We sadly need to special case these two because the name does
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* not match the VFL grammar rules
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*/
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if (strcmp (name, "centerX") == 0)
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return GTK_CONSTRAINT_ATTRIBUTE_CENTER_X;
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if (strcmp (name, "centerY") == 0)
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return GTK_CONSTRAINT_ATTRIBUTE_CENTER_Y;
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for (int i = 0; i < G_N_ELEMENTS (attribute_names); i++)
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{
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if (strcmp (attribute_names[i], name) == 0)
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return i;
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}
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return GTK_CONSTRAINT_ATTRIBUTE_NONE;
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}
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/**
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* gtk_constraint_layout_add_constraints_from_description:
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* @layout: a #GtkConstraintLayout
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* @lines: (array length=n_lines): an array of Visual Format Language lines
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* defining a set of constraints
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* @n_lines: the number of lines
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* @hspacing: default horizontal spacing value, or -1 for the fallback value
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* @vspacing: default vertical spacing value, or -1 for the fallback value
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* @views: (element-type utf8 Gtk.Widget): a dictionary of [ name, widget ]
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* pairs; the `name` keys map to the view names in the VFL lines, while
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* the `widget` values map to children of the widget using a #GtkConstraintLayout
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*
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* Creates a list of constraints they formal description using a compact
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* description syntax called VFL, or "Visual Format Language".
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*
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* The Visual Format Language is based on Apple's AutoLayout [VFL](https://developer.apple.com/library/content/documentation/UserExperience/Conceptual/AutolayoutPG/VisualFormatLanguage.html).
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*
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* The @views dictionary is used to match widgets to the symbolic view name
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* inside the VFL.
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*
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* The VFL grammar is:
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*
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* |[<!-- language="plain" -->
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* <visualFormatString> = (<orientation>)?
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* (<superview><connection>)?
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* <view>(<connection><view>)*
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* (<connection><superview>)?
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* <orientation> = 'H' | 'V'
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* <superview> = '|'
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* <connection> = '' | '-' <predicateList> '-' | '-'
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* <predicateList> = <simplePredicate> | <predicateListWithParens>
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* <simplePredicate> = <metricName> | <positiveNumber>
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* <predicateListWithParens> = '(' <predicate> (',' <predicate>)* ')'
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* <predicate> = (<relation>)? <objectOfPredicate> (<operatorList>)? ('@' <priority>)?
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* <relation> = '==' | '<=' | '>='
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* <objectOfPredicate> = <constant> | <viewName> | ('.' <attributeName>)?
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* <priority> = <positiveNumber> | 'required' | 'strong' | 'medium' | 'weak'
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* <constant> = <number>
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* <operatorList> = (<multiplyOperator>)? (<addOperator>)?
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* <multiplyOperator> = [ '*' | '/' ] <positiveNumber>
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* <addOperator> = [ '+' | '-' ] <positiveNumber>
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* <viewName> = [A-Za-z_]([A-Za-z0-9_]*) // A C identifier
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* <metricName> = [A-Za-z_]([A-Za-z0-9_]*) // A C identifier
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* <attributeName> = 'top' | 'bottom' | 'left' | 'right' | 'width' | 'height' |
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* 'start' | 'end' | 'centerX' | 'centerY' | 'baseline'
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* <positiveNumber> // A positive real number parseable by g_ascii_strtod()
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* <number> // A real number parseable by g_ascii_strtod()
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* ]|
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*
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* **Note**: The VFL grammar used by GTK is slightly different than the one
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* defined by Apple, as it can use symbolic values for the constraint's
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* strength instead of numeric values; additionally, GTK allows adding
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* simple arithmetic operations inside predicates.
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*
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* Examples of VFL descriptions are:
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*
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* |[<!-- language="plain" -->
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* // Default spacing
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* [button]-[textField]
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*
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* // Width constraint
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* [button(>=50)]
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*
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* // Connection to super view
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* |-50-[purpleBox]-50-|
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*
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* // Vertical layout
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* V:[topField]-10-[bottomField]
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*
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* // Flush views
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* [maroonView][blueView]
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*
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* // Priority
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* [button(100@strong)]
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*
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* // Equal widths
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* [button1(==button2)]
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*
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* // Multiple predicates
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* [flexibleButton(>=70,<=100)]
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*
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* // A complete line of layout
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* |-[find]-[findNext]-[findField(>=20)]-|
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*
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* // Operators
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* [button1(button2 / 3 + 50)]
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*
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* // Named attributes
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* [button1(==button2.height)]
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* ]|
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*
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* Returns: %TRUE if the constraints were added to the layout
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*/
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gboolean
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gtk_constraint_layout_add_constraints_from_description (GtkConstraintLayout *layout,
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const char * const lines[],
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gsize n_lines,
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int hspacing,
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int vspacing,
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GHashTable *views,
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GError **error)
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{
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GtkConstraintVflParser *parser;
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g_return_val_if_fail (GTK_IS_CONSTRAINT_LAYOUT (layout), FALSE);
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g_return_val_if_fail (lines != NULL, FALSE);
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g_return_val_if_fail (views != NULL, FALSE);
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g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
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parser = gtk_constraint_vfl_parser_new ();
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gtk_constraint_vfl_parser_set_default_spacing (parser, hspacing, vspacing);
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gtk_constraint_vfl_parser_set_views (parser, views);
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for (gsize i = 0; i < n_lines; i++)
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{
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const char *line = lines[i];
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GError *internal_error = NULL;
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gtk_constraint_vfl_parser_parse_line (parser, line, -1, &internal_error);
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if (internal_error != NULL)
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{
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int offset = gtk_constraint_vfl_parser_get_error_offset (parser);
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int range = gtk_constraint_vfl_parser_get_error_range (parser);
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char *squiggly = NULL;
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if (range > 0)
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{
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squiggly = g_new (char, range + 1);
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for (int r = 0; r < range; i++)
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squiggly[r] = '~';
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squiggly[range] = '\0';
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}
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g_set_error (error, GTK_CONSTRAINT_VFL_PARSER_ERROR,
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internal_error->code,
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"%" G_GSIZE_FORMAT ":%d: %s\n"
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"%s\n"
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"%*s^%s",
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i, offset + 1,
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internal_error->message,
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line,
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offset, " ", squiggly != NULL ? squiggly : "");
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g_free (squiggly);
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g_error_free (internal_error);
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gtk_constraint_vfl_parser_free (parser);
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return FALSE;
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}
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int n_constraints = 0;
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GtkConstraintVfl *constraints = gtk_constraint_vfl_parser_get_constraints (parser, &n_constraints);
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for (int j = 0; j < n_constraints; j++)
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{
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const GtkConstraintVfl *c = &constraints[j];
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gpointer source, target;
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GtkConstraintAttribute source_attr, target_attr;
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target = g_hash_table_lookup (views, c->view1);
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target_attr = attribute_from_name (c->attr1);
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if (c->view2 != NULL)
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source = g_hash_table_lookup (views, c->view2);
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else
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source = NULL;
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if (c->attr2 != NULL)
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source_attr = attribute_from_name (c->attr2);
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else
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source_attr = GTK_CONSTRAINT_ATTRIBUTE_NONE;
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GtkConstraint *constraint =
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gtk_constraint_new (target, target_attr,
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c->relation,
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source, source_attr,
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c->multiplier,
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c->constant,
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c->strength);
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layout_add_constraint (layout, constraint);
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g_hash_table_add (layout->constraints, constraint);
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}
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g_free (constraints);
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}
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gtk_constraint_vfl_parser_free (parser);
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return TRUE;
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}
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@ -76,4 +76,13 @@ GDK_AVAILABLE_IN_ALL
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void gtk_constraint_layout_remove_guide (GtkConstraintLayout *manager,
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GtkConstraintGuide *guide);
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GDK_AVAILABLE_IN_ALL
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gboolean gtk_constraint_layout_add_constraints_from_description (GtkConstraintLayout *manager,
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const char * const lines[],
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gsize n_lines,
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int hspacing,
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int vspacing,
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GHashTable *views,
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GError **error);
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G_END_DECLS
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