Navigation

OPBrowser connects its engine-level navigation history to a native address bar, Go/Back/Forward/Reload buttons and keyboard shortcuts. The engine remains separate from Windows controls so the same history rules can later be used by tabs.

Start target\release\op_browser.exe, enter https://example.com and press Enter or Go. An explicit HTTP/HTTPS URL can also be the first command-line argument. Ctrl+L selects the address, F5 reloads, and the mouse wheel scrolls the document. Blue, underlined page links are clickable and show a hand cursor. The start page contains an Example Domain link; examples/navigation/index.html demonstrates local relative navigation.

State

NavigationState stores:

• an ordered list of NavigationEntry values;
• the current history index;
• the original request string;
• the normalized loaded address;
• the loaded MIME type.

Operations

Engine exposes:

• navigate(source): loads/renders and commits a new history entry;
• follow_link(href): resolves against the last successfully loaded document address, then performs normal navigation;
• go_back(): reloads the previous historical request;
• go_forward(): reloads the next historical request;
• reload(): reloads the current request without adding a history entry.
• reflow(): rebuilds layout/paint from retained DOM/images without fetching or changing history; resize input invokes this on the same worker.

Invariants

History mutation is commit-after-success. A failed load does not create a broken history entry or change the current index.

A new navigation after going Back discards the old forward branch, matching normal browser-session behavior.

Back, forward and reload do not create duplicate entries.

Native event path

The window translates Enter and button/shortcut input into NavigationEvent values. Button commands are queued out of the window procedure to avoid callback reentry. op_browser sends a command plus viewport dimensions to a single worker that owns Engine. It loads/renders and sends the page and history-button flags to the UI. Only the UI thread replaces the display list, updates controls and repaints.

A Win32 timer polls results every 30 ms while loading; it is stopped when loading finishes. The status line shows Loading, Layout, Ready or the load error. Navigation is serialized: buttons are disabled and further navigation shortcuts are ignored while a request is in flight. Paint, address editing, scroll and close stay live. A failed load keeps the previous page and history, allowing correction of the URL.

Current limits

Pages show static HTML text with heading/paragraph defaults, including blocks inside structural containers. Links open in the current window through the worker and history. Inline href spans survive line wrapping; native hit regions are measured from painted glyphs, adjusted for scroll and cleared on display replacement. Relative network links use the final response URL, including redirects on reload; local pages support relative filesystem links. Unsupported schemes show a load error and preserve the previous page. They never launch another application.

PNG/JPEG/GIF/BMP images and image links now participate in the same worker/history path; see Image Loading for bounds and Inline Layout for mixed text/image lines. CSS and JavaScript remain future work. Fragment-only links reload without anchor scrolling; HTML base elements and target/download behavior remain future work. Resizing moves controls immediately and reflows retained page data after a 120 ms pause. It preserves address edits and pixel scroll within the new bounds, rebuilds link hit regions and changes no history. See Page Reflow.

All standard named/numeric references decode in href attributes before layout, so links such as ?a=1&b=2 navigate to ?a=1&b=2. Back/Forward fetch the historical request again; there is no page cache yet.