Building Mobile Applications with MIT App Inventor - كتاب هندسة البرمجيات - الصف 12 - الفصل 1 - المملكة العربية السعودية

--- SECTION: Reference to Logic Blocks --- The blue circle labeled '1' points to the 'and' and 'or' logic blocks, as well as the equality comparison block, within the conditional statement of the 'riyadh_list.AfterPicking' event handler in the first App Inventor screenshot. --- SECTION: Reference to Variable Blocks --- The blue circle labeled '2' highlights the 'get' block, used for retrieving a variable's value, shown alongside other variable initialization and assignment blocks in the second App Inventor screenshot. --- SECTION: Page Footer --- وزارة التعليم Ministry of Education 2023 - 1447 166 --- VISUAL CONTEXT --- **DIAGRAM**: MIT App Inventor Interface: Logic Blocks and Conditional Statement Description: A screenshot of the MIT App Inventor 'Blocks' editor. The top bar shows 'Projects', 'Connect', 'Build', 'Settings', 'Help'. The app title is 'Visit_SA_App' with buttons 'Cities', 'Add Screen', 'Remove Screen', 'Publish to Gallery'. The left panel, labeled 'Blocks', lists 'Built-in' categories: 'Control', 'Logic', 'Math', 'Text', 'Lists', 'Dictionaries', 'Colors', 'Variables', 'Procedures'. Below 'Built-in', the 'Cities' component category is shown with 'discover_label', 'VerticalArrangement1', 'cities_label', 'riyadh_list', 'jeddah_list'. The right panel, labeled 'Viewer', displays several logic blocks: 'true', 'false', 'not', an equality comparison block '=', 'and', and 'or'. A larger code block is visible, starting with 'when riyadh_list . AfterPicking do'. Inside, it contains 'set global selection to riyadh_list . Selection', followed by an 'if' block. The 'if' condition includes an 'or' block, which contains two 'get global selection =' blocks. The 'then' part of the 'if' block is empty. A blue circle with the number '1' points to the 'and' and 'or' blocks. Table Structure: Headers: N/A Data: The visual elements demonstrate the graphical block-based programming environment of MIT App Inventor, specifically focusing on logical operations and conditional flow control within an event handler. Key Values: MIT APP INVENTOR, Visit_SA_App, Blocks, Viewer, Built-in, Logic, true, false, not, =, and, or, when riyadh_list . AfterPicking, set global selection to riyadh_list . Selection, if, then, get global selection Context: This diagram illustrates how to construct conditional logic using 'if-then' statements and boolean operators ('and', 'or', 'not', '=') in MIT App Inventor to respond to user interactions, such as selecting an item from a list ('riyadh_list.AfterPicking'). **DIAGRAM**: MIT App Inventor Interface: Variable Initialization and Assignment Blocks Description: A second screenshot of the MIT App Inventor 'Blocks' editor. The top bar shows 'Projects', 'Connect', 'Build', 'Settings', 'Help'. The app title is 'Visit_SA_App' with buttons 'Cities', 'Add Screen', 'Remove Screen', 'Publish to Gallery'. The left panel, labeled 'Blocks', lists 'Built-in' categories: 'Control', 'Logic', 'Math', 'Text', 'Lists', 'Dictionaries', 'Colors', 'Variables', 'Procedures'. Below 'Built-in', the 'Cities' component category is shown. The right panel, labeled 'Viewer', displays blocks related to variable handling: 'initialize global name to', 'get', 'set to', and 'initialize local name to in'. A blue circle with the number '2' points to the 'get' block. Table Structure: Headers: N/A Data: The visual elements demonstrate blocks for declaring and manipulating variables in MIT App Inventor. Key Values: MIT APP INVENTOR, Visit_SA_App, Blocks, Viewer, Built-in, Variables, initialize global name to, get, set to, initialize local name to in Context: This diagram demonstrates the fundamental blocks for defining global and local variables, retrieving their current values ('get'), and assigning new values ('set') within the MIT App Inventor programming environment. **DIAGRAM**: MIT App Inventor: 'AfterPicking' Event Handler (Partial) Description: A standalone code block, identical to the larger code block shown in the first screenshot. It represents an event handler: 'when riyadh_list . AfterPicking do'. Inside, it sets a global variable: 'set global selection to riyadh_list . Selection'. This is followed by an 'if' block containing an 'or' condition, which checks if 'get global selection =' (twice). The 'then' part of the 'if' block is empty. Table Structure: Headers: N/A Data: This block shows a specific event handler with variable assignment and conditional logic. Key Values: when riyadh_list . AfterPicking, do, set global selection to riyadh_list . Selection, if, or, get global selection =, then Context: This block serves as a detailed example of how to implement an event-driven action in MIT App Inventor, specifically handling the selection of an item from a list and applying conditional logic based on that selection.